Air Conditioner & Heat Pump Troubleshooting FAQs

Troubleshoot Air Conditioners & Heat Pumps Q&A Set#3

A/C or Heat Pump Runs but Doesn't Provide Cool Air FAQs

My A/C Unit Blows Warm Air, I'm doing some of the repair and it's not going well

My A/C unit is blowing warm air. The repairman added a pound of freon and recommended I add a stop leak additive to the system.

I added it but the air still wasn't as cool as it should be. He came back out, said I had "low head pressure" and may need new TXV if adding more freon didn't help.

It didn't, so I called him out to replace the txv and he found the A-coil was extremely dirty. He cleaned it as well as he could with my vacuum and said He could cut it out, acid bathe it and reinstall for around $550 or I could try cleaning it myself with coil cleaner

I opted to try it myself. After he left, I noticed the condensor fan outside only runs for about 15 minutes then shuts off. I have to turn off the system and let it set for 30 minutes or so before trying again but it still shuts down.

With the thermostat set to 73 degrees, it's running closer to 80 (I had to buy a window unit to survive our 100 degree days). Any ideas? On 2015-07-20 by A/C issues-blowing warm air

Reply by (mod) -

A/C

I'm nervous about the prospect of the "stop leak" product clogging up the thermostatic expansion valve (TXV). Of course if it does clog up the valve then that's nice for the service company.

Watch out: if you're not trained on HVAC repair and if you don't have the proper charging equipment, there's risk that you contaminate the system and cause damage.

Followup by A/C - system was barely cooling - added refrigerant

Last summer, the system wasn't cooling. The repairman added 2 lbs of refrigerant and everything was okay. This summer, again, the system wasn't cooling. Serviceman came out, added a pound of refrigerant and said I should put in the AC Leak freeze because it shouldn't have lost a pound. I added it but am still having issues.

When I say "With the thermostat set to 73 degrees, it's running closer to 80..." I mean the thermostat registers 80 degrees. Sorry for the confusion. The coil is getting mildly cool as well as the outside line.

The system is barely cooling and the outside (condensor) fan runs for about 15 minutes then shuts off. It used to run as long as the inside blower was running. I'm not sure what else to try but I'm getting tired of paying the service guy $100+ every week with no change.

Reply by (mod) -

Now AC, continuing the diagnostic suggestion:

You say your system runs but is not producing cool air - "With the thermostat set to 73 degrees, it's running closer to 80 (I had to buy a window unit to survive our 100 degree days)."

If you mean that air delivered from the supply registers is at 80F then the system is not cooling. If the compressor is working and the refrigerant charge is correct you should feel cool or cold suction lines at the compressor and you should be able to measure a temperature drop across the evaporator (cooling) coil at the air handler.

If the cooling coil is not getting cold then most likely there is a problem with the charge or the refrigerant metering device.

See REFRIGERANT LEAK SEALANT USE

for a discussion of using leak sealants

Adding 2 lbs of refrigerant means your system was probably close to empty.

Even on a large system holding 5-8 pounds of refrigerant, that's still a pretty big leak. A pound a year is a big refrigerant leak for any A/C or heat pump system.

Normally a refrigeration system loses ZERO refrigerant. The charge is permanent unless there is a leak.

A dirty evaporator (cooling) coil will also reduce the cooling out put of a system because it blocks air flow. You may find the cooling coil also ices over because of the reduced air flow across it.

To distinguish between low refrigerant and a dirty coil (or dirty air filter or other duct defect) for the homeowner is relatively simple. If the air flow at your supply registers is weak I suspect one of the latter issues. If the air flow is strong but the air is not cool I suspect low refrigerant or a TEV that's not metering refrigerant properly.

At AIR CONDITIONER TEMPERATURE MEASUREMENT  we describe how to measure A/C temperatures for diagnostic purposes.

At AIR CONDITIONER TEMPERATURES we give typical A/C system temperatures you should find.

If your A/C system can't get the indoor temp below 80, unless you've got windows and doors open or some unusual heat gain situation, your A/C system is not working.

Watch out: If your system is leaking refrigerant as it seems to be from your description, especially where the leak is a significant one, you need to have a the leak point found and fixed. Don't just keep adding refrigerant: that's pouring your money as well as environmental contaminants into the atmosphere.

Followup by ac

The specs for my unit says unit charge is 7 pounds 3 ounces. The filter was slightly dirty but the coil was definitely clogged.

Once it was vacuumed off (still needs some cleaning) the air flow out of the vents increased quite a bit but it is still not cool air and doesn't explain the condensor fan stopping. The cooling coil is definitely not icing over-it barely gets cool and no windows or doors open.

Reply by (mod) -

The condensor fan runs or not under control of the compressor/condenser control board and switches. If the compressor is not running the condenser fan will stop. If the compressor fan is running without the fan then indeed a repair is needed.

If your system outdoor and indoor units run and blows out of supply vents but is only warm then no coolant is entering the cooling coil. That's a charge or a refrigerant metering device problem (most likely).

A service tech will check high and low side pressures and may need to adjust, clean or replace the thermostatic expansion valve if the charge is proper.

Our A/C unit has lost cooling capacity

I checked all of the basic things, changed filters, replaced thermostat, etc. We changed the compressor last year. The shut off valve seems to be okay. And, we replaced the attic fan last month. What could be the issue? - Anon

I live in an apartment complex and this weekend the air conditioner stop blowing cool air. I called maintenance and they came over to repair the problem.

He removed some plastic tube and drained water from it and said that was the problem. Two hours later it stops blowing cool air again.

Needless to say, I called them back over and he informed me that I would have to drain that tube (line) ever time it goes out or call them. Is this correct? Should I have to drain a tube (line) for my air conditioner to work properly? - WB

Reply by (mod) -

Anon: At DIAGNOSTIC GUIDE A/C or HEAT PUMP we list A/C problems that could be the issue - I'm afraid that if you've read through and been through all of those diagnostics and did not see something obvious such as a dirty filter or lost electrical power, then it's time to call in an expert HVAC technician to diagnose the problem and then to describe the repairs s/he recommends.

WB: I can only guess with so little info, but if your A/C system has a condensate pan that uses a condensate pan overflow safety switch, then that could be shutting your system down.

If the condensate pan stops draining - say from a clogged drain - the switch senses water accumulating in the pan and will turn off the system to avoid flooding the building.

Or it could be a different problem. It's time for your maintenance people to bring in someone who is qualified on air conditioning diagnosis and repair.

Upstairs A/C works but downstairs air isn't cool

I have a duplex that has both levels sharing one central air unit. The upper level is working perfect. The lower levels air is blowing fine but the air isnt cool at all. by AC

Reply by (mod) - no cool air on some floors

AC
I'd double check that ALL of the air conditioning is provided really by a single system and that your thermostat is set on COOL not FAN.

A/C keeps running but doesn't cool down enough indoors

I have the A/C thermometer inside set at 78 degrees. The temperature in the house is at 82 The unit continues to run but doesn't seem to cool enough to reduce the inside temp. I worry that it's running much too long. Help! Marty

Reply by (mod) -

Long running without cooling adequately could be due to many of the possible explanations we list in the article above;

Check the output air temperature at the cooling coil to be sure it's actually cooling, and if so, check for air flow restrictions like a dirty filter. If the system used to cool the building adequately under the same weather conditions, we tend not to suspect that it was under-sized and we look for an operating problem.

Mobile home wall unit not cool enough

Is there a general expected temp required for a wall unit? Mobile home has a wall unit but it seems that the output temp is only cool not cold. How can I determine if unit is working properly? On 2011-10-03 by Gary Johnson

by (mod) -

Gary, see OPERATING TEMPERATURES HVAC

Outside compressor/condenser not running and no cool air inside

The AC unit runs but no cool air and no fan running outside, the unit is very hot to the touch.

My Main central Air unit outside is very hot and the fan is not running but still running, The smaller unit is still running fine. I have two because my house is very big 3600 SqFt. Do I need to get a new Central air unit? On 2011-08-26 by Thomas

by (mod) - Lost Cooling Capacity

Thomas I can't say you need a new unit before there has been an accurate diagnosis of the problem. When the outside compressor/condenser is not running you won't get cool air inside; but the problem could be a simple as a switch or control relay, or as serious and costly as a bad compressor.

Hot to touch sounds like a compressor motor that is not starting but I'm just guessing from so little info.

Under the LOST COOLING CAPACITY article (Found in INDEX to RELATED ARTICLES at our Continue reading suggestions at the end of this article) you'll see a link to

Compressor Diagnosis: Diagnose & Repair

I'd take a look at that info as well as calling an HVACR service company. Keep us posted.

A/C Runs but Cooling Capacity Isn 't Enough FAQs

insufficient cooling

About a week ago we started noticing insufficient cooling of our 1000sq ft condo unit by our heat pump. We replaced a very dirty AC unit filter, and ran various checks as you recommended above. Later that same day, the temperature began steadily rising in our unit...the air was blowing but no cool air out of the vents at all.

We got opinions from two AC repair companies, both of whom said the compressor needed to be replaced.

Luckily, the part was under warranty (the unit is only appx 3 yrs old and we are the first to live in it). It took a good 48 hours or so for the place to become cool again after the work was complete.

And now, a week later, it still does not seem to be as cool as it should be.

Overnight, the temp drops as we want, but the AC seems to run all day. Tonight, for example, the thermostat has been set on 75 for the past 6 hours, the AC has not gone off in those 6 hours, and the thermostat still reads 79 degrees.

A thermometer in the vent reads 68 degrees. We are in central Texas, and the temperatures have been over 100 for 70+ days (110 today actually)...but I'm not sure that I should totally write this off as the reason for insufficient cooling. Am I just being paranoid, or should I assume there is still a problem? On 2011-08-28 by Sarah -

by (mod) - new compressor is not cooling as well as the old system

Sarah:

If your new compressor is not cooling as well as the old system did and the capacity was properly matched, I wonder if the refrigerant charge was correct? A check of the air temperature drop ACROSS THE COOLING COIL should find between 15 and 22 degF.

If you're seeing that temperature drop at the coil the A/C system is operating normally in all other respects (no dirty blower fan, good airflow, etc), then it seems possible that the too-hot conditions in the home could be due to weather, house heat gain, and adequacy of the whole A/C system to start with

A/C or Heat Pump Won't Start, Won't Run or Won't Keep Running

Outside Compressor Motor Won't Run

The outside unit fan runs fine but compressor motor itself does not start - Tim

On 2011-10-12 by (mod) - outside fan runs good but compressor does not

Tim, as your A/C compressor is not running you need some diagnosis and repair. It might be something minor like a starting capacitor, or a larger problem such as a burned out compressor motor.

See these diagnostic procedures

• AIR CONDITIONER WON'T START

AC Won't Cool - outside unit won't come on

My AC wont cool. I have checked the filter and is clean. The air handler is clear. The air handler stays on and the out side unit will not come on the unit is 2 years old

I cut the power to switches and reset them. The out side unit came on for the night and now will not turn on. I push in the relay on the out side unit and he house starts to cool but when I let go it shuts off again. On 2011-08-27 by Peter

On 2011-09-01 by (mod) - hard starting compressor

Peter:

sounds like a hard starting compressor; ask the hvac tech about a start/run capacitor kit.

A/C or Heat Pump Thermostat FAQs

Thermostat wiring found disconnected

I have a central HVAC system, electric haet and AC. this is in a condo i bought. i found the wiring to the thermostat DISCONNECTED when i bought the place. i think the prior owner was upset about getting foreclosed on and decided to leave me a "present".

anyway, i looked at a neighbour's thermostat and wired it up exactly like hers. now, the fan comes on as it should and the AC compressor kicks on when i tell it to cool by setting the temp to lower than in the unit. HOWEVER, i get no cold air blowing!

I also cannot get any hot air when I set the thermostat to go higher than room temp. the thermostat is a honeywell T8100C. does anyone have any ideas? thx! On 2011-09-05 by paul

Reply by (mod) -

Paul often people leave something disconnected not out of malice but because it's not working properly and they just don't want to deal with it. I'm presuming you bought without a home inspection - else the inspector would have most likely tried turning on the system and you'd have had a warning about this repair.

Also foreclosed homes are often ones at which repairs and maintenance have been let go - people who are not paying on the mortgage are also not doing home repairs.

It's possible that a heater control board or actual heating elements have failed in your unit. Take a look at

BACKUP HEAT for HEAT PUMPS (in the INDEX to RELATED ARTICLES found at the end of this discussion) for help in diagnosing electric heaters that aren't working

Switching Between Cooling & Heating Mode FAQs

Do refrigerant lines need to "rest" when switching from heating to cooling mode?

My apartment manager has shut off the heat in our building and is transitioning to A/C (only one works at a time).

They sent out an email stating "we have shut the heat down and now have to let the lines rest and come to temperature before we can start the AC."

I've never heard of lines "needing to rest" before using the air conditioner (I'm from the south but I moved to New England this year)

Is there something different about A/C units here that makes this necessary? Does this sound legitimate, or is the manager pulling our chains? - On 2017-05-19 by Anonymous

Reply by (mod) - 24 hours would be more than enough to swap between heating/cooling modes,

Typically 24 hours would be more than enough to swap between heating/cooling modes, and even then the problem being avoided would be avoiding turning on an air conditioner or heat pump in cold weather.

Is it ok to set upstairs heat thermostat way down in winter?

I have a two story house with dual units. No one uses the upstairs while my daughter is in college.

I turned the thermostat way down in the winter, and way up in the summer, so that I'm not heating and cooling an entire floor of a house that isn't used.

I was told by a friend that this is really bad on my unit, which is relatively new, is this true?

Do I need to go back to the four degree difference between the two units? On 2016-12-05 by Anonymous -

Reply by (mod) - Yes

No you do not. An air conditioning system should not be damaged by leaving it turned off or set to temperatures reducing its run-time.

A/C Heat Pump Compressor / Condenser Unit Repair vs Replacement FAQs

Because Q&A on this topic often involves decisions about replacing components in either or both the indoor and outdoor A/C or heat pump equipment you may want to see both

AIR HANDLER BLOWER UNIT REPAIR vs REPLACE FAQs - replace the evaporator coil, replace the whole unit?

and

COMPRESSOR / CONDENSER UNIT REPAIR vs REPLACE FAQs - repair vs replace? - you are in this section

Replace Seized Compressor & AHU Coil or Replace Whole Units?

Need some help in deciding what to do with seized-up compressor (replace just the compressor and the coil at the air handler or replace the entire condensor/compressor unit along with new coils in the air handler). Current system is a 3-ton 10SEER unit with Copelant scroll compressor & R22 refrigerant

If I replace just the compressor & coils (to equivalent parts), but charge it with R410A refrigerant, would it still be compatible with the existing condensor? Is it typical to replace the TXV (or TEV) valve when replacing the air handler coils? Contractors are pushing towards replacing the entire condenser/compressor & coils (at a significantly higher cost). On 2011-08-06 by TN-Goose

by (mod) - when a compressor trips the CB immediately on turn-on

TN, when a compressor trips the CB immediately on turn-on, there is a short somewhere, or the motor is shorting out or drawing very high amps at startup. That's what your tech found and it's consistent with a seized compressor motor. Your ductwork indoors at the air handler doesn't sound like a source of compressors blowing a circuit breaker.

And what the tech said about R22 no longer in use is quite correct. You'd either go to R410A which works similarly to the old refrigerant but not precisely the same, or ...

On replacing a seized-up compressor, if the new compressor is matched to the rest of the system one wouldn't necessarily think about changing rest of the system components.

However because the new compressor will also use a new refrigerant, the installer may want to compatible key components throughout: the condensing coil, evaporator coil, and refrigerant metering device (TEV), possibly other controls all to work properly with the new refrigerant.

By the time you pay for the labor to R&R coils indoors and outside as well as other parts, you can understand why the HVAC company wants to install everything new - it may be less labor, faster installation, and perhaps even more profitable.

Followup by TN-Goose: short circuit in compressor motor

Had Service tech check out my 3-ton compressor, which has been tripping the breaker immediatly upon turning ON.

Tech checked the resistnace of compressor terminals and noted that it has a short-circuit.

Says the cause of compressor short-circuit can be caused by rapid power ON-OFF from storms, and/or undersized duct diameter in the blower of the air handler in the attic.

My duct size is 14" on one side and 16" on the other side of the air handler.

Is there any truth in 14" diameter duct causing a 3-ton scroll compressor to seize-up/short-out?

Tech also it's illegal to recharge with R22 refrigerant; must use R410A. Is this true?

Reply by (mod)

OPINION: duct design defects might make the whole A/C or heat pump system run longer to satisfy the thermostat but it'd be a big leap from that problem to claiming that the indoor duct system caused the outdoor compressor motor to seize.

Other problems can kill a compressor motor, such as liquid slugging, over-charging, or refrigerant oil return problems.

And yes, R22 refrigerant is no longer permitted in A/C repair or installation.

While your system might run acceptably with R410A it's not designed for it.

 

Our A/C Compressor is completely shot. Is the replacement cost reasonable?

My central air tripped the breakers and I swithched it back on. It worked for one night and tripped again the following morning. Now cold air wouldn't come out so I called a tech. He was testing the compressor with a booster(?) and a pop sounded and tripped the entire house of electricity.

We had re set the main fuse box and he later said the compressor is completely shot.

We have a 3.5 ton condenser and he quoted me $1500 for just the compressor with a warranty of 6 months and recommended the entire condenser to be replaced since the warranty would last 5 years. Are the prices and what would be your suggestion? On 2011-08-28 by Jeremy -

Reply by (mod) - AC unit trips breakers

Jeremy an A/ C unit that trips breakers is probably drawing too much current - a sign of a hard starting or seizing compressor.

So what your tech says sounds credible.

The price sounds low for New York and normal for some other areas.

Do we replace a bad compressor or the whole condenser unit?

If either the compressor or condenser is bad, must they both be replaced? On 2016-06-29 by Tishtash

Reply by (mod) -

Tish

The compressor is the motor that is compressing suction-side low-pressure refrigerant gas into a high pressure gas. The outlet from the compressor flows through a condensing coil - looks a bit like a car radiator with fins and tubing. A fan blows outdoor air across the coil to cool it.

That causes the high pressure high temperature gas to cool back to a liquid refrigerant state, and in the process of removing that heat from the refrigerant we're in effect moving heat from the building interior to outdoors.

Now if just the compressor motor has failed, that's a replaceable unit.

If just the condensing coil has failed - say by corrosion and leakage, that's a replaceable unit.

If just the fan or fan motor has failed, that's a replaceable unit.

The whole outdoor assembly is referred-to as the "Compressor/Condenser Unit".

The decision to replace the whole compressor/condenser unit versus replacing one or more of its parts would turn on several points:

- what's the age of the unit?

- is the exiting unit using a no-longer available refrigerant?

- what will be the total cost to repair individual failed components with the total installed-cost to replace the whole compessor/condenser unit?

Signs of a Failed A/C compressor motor

Have an 11 year old compressor/fan unit that kicked off the breakers and now will not run at all. Replaced the capacitor, still no soap, although it is not kicking off the breaker now. Checked the fan motor for a reset button, and there isn't one. Any suggestions short of calling the serviceman? On 2011-08-22 by Jeff Huston

by (mod) - sounds like a bad compressor or other motor

Jeff:

I'm sorry to say you needed to call an HVACR tech. It sounds like a bad compressor or other motor that has failed.

It could be an electrical short - a short circuit might trip the breaker but also burn the wire enough that when you turn power back on there is no actual electrical connection - the circuit has become "open".

Indoor Air Handler Repair vs Replace FAQs

Because Q&A on this topic often involves decisions about replacing components in either or both the indoor and outdoor A/C or heat pump equipment you may want to see both

AIR HANDLER BLOWER UNIT REPAIR vs REPLACE FAQs - replace the evaporator coil, replace the whole unit? - you are in this section

and

COMPRESSOR / CONDENSER UNIT REPAIR vs REPLACE FAQs - repair vs replace?

New cooling coil doesn't fit my existing indoor air handler

I need to replace my A/C on the outside of my house and the indoor air handler's evaporator coil.

My problem is that my existing furnace has a 13in wide evaporator coil and I can't find that size anywhere. The smallest I can find are 14 and 14.5 inch.

Can I use a bigger evaporator coil on my furnace? What would be need to do so? Thank you! On 2023-05-30 by Ben - N

Reply by InspectApedia Publisher (mod) - Upflow furnace installation of an add-on cooling coil or evaporator coil

@Ben,

Yes you can use a larger evaporator coil, but be sure to discuss with the installer just how the air plenum should be shaped for best air flow across the coil.

Watch out: if your new coil is too large for the system's design it may cool the building without adequate dehumidification (because it cools everything down too fast to complete moisture removal).

The transition plenum that you install will be shaped to direct air flow across the coil without creating dead air spaces.

Don't just slap on a larger coil atop the air handler, sticking out at the sides.

Here is an often-quoted excerpt from Trane's IO manual

FURNACE UPFLOW INSTALLATION

Standoffs and screws (See Figure 1, page 6) are included with the cased coils for attachment to the furnace. NOTE: The top flanges on the furnace must be bent 90 degrees upward to allow the coil attachment.

There are clearance alignment holes near the bottom of the coil wrapper. Drill screws are used to engage the furnace top flanges. The standoff is inserted into the cabinet alignment hole.

The drill screws are inserted through the standoffs then screwed into the furnace flange. The coil is always placed downstream of the furnace airflow. The above instructions apply only if the coil is on top of an upflow furnace.

COIL

a. Apply gasket material (duct seal field supplied) to ALL mating surfaces between the furnace and the coil case.

b. Set the coil case on top of the furnace. Connect the ductwork to the coil case using the field supplied screws.

c. Secure the coil case to the furnace and seal for air leaks as required.

Is it better to replace the cooling coil or to buy a whole new air handler?

Is is worth replacing coils on a/c or better to buy new unit? - On 2012-09-13 by debbie

Reply by Mod

Debbie:

The choice to repair versus replace air conditioning or heat pump equipment depends on answers to a few questions to put to your repair technician:

How old is the system?

What refrigerant is it using? (If it's an older unit that uses a discontinued refrigerant such as R22 it's often better to replace the equipment).

What is the problem with the cooling coil on your system: dirty versus leaky?

Typical cost to replace the cooling or evaporator coil is in the $1400 - $2000 range (USD) depending on coil size and accessibility.

Typical cost to replace the entire indoor air handler (including the blower unit, furnace, cooling coil, etc.) is about $1500 for the equipment and another $1500 or more (depending on where you live) for installation labor.

Comparing those prices, most technicians will recommend installing a new unit (air handler) if your system is an older one.

On a newer A/C system in good condition but with a damaged coil that needed replacement, I'd consider that move.

What does your heating tech say?

Thermostatic Expansion Valve TEV TXV FAQs

Can a bad Thermostatic Expansion Valve cause the compressor motor to "short out"?

Can a faulty TXV (TEV) cause the compressor to short-out? On 2011-08-06 by TN-Goose

Reply by (mod) - it may harm the compressor but "short out" ? not so sure.

A bad TEV can cause abnormal system pressures, including excessive high side pressure that one would hope would cause a safety control to stop the system.

But I don't know why it'd cause a short circuit - maybe due to excessive current draw from a failed motor?

None of us knows it all, but that failure is not one we learned about in my HVAC classes.

On 2011-08-06 by TN-Goose - information on the effect of TXV on compressor - Hunting

I found this information on the effect of TXV on compressor.

TXV superheat set too low:

The superheat must be allowed to change in order for the sensing bulb to make corresponding adjustments to the valve opening while it maintains the set superheat.

A low superheat setting can allow the superheat to fall to zero. This condition will cause the valve to close and the superheat will soon rise well above its setting.

This in turn can cause the valve to reopen wider than necessary and overshoot the superheat setting.

This condition is called hunting. On one of the valve's swings to the wide open position, liquid refrigerant can flood the suction line and allow liquid to enter the compressor, a potentially damaging condition.

by (mod) - Superheat and hunting thermostatic expansion valve -

Thanks for that detail about superheat and hunting thermostatic expansion valve - I'll be sure the text is added to the TEV article.

In other words, an improper TEV setting can cause rapid opening/closing of the valve resulting in liquid refrigerant flooding the suction line, entering the compressor motor. Because compressor motor moving parts and valves are designed to compress a gas, and because a liquid (refrigerant) is not particularly compressible, the compressor motor, piston, crank, or more immediately its refrigerant valves are likely to be damaged or destroyed.

It is possible that dirt, debris, or even water in the refrigerant piping system and that enters the TEV could cause this malfunction by freezing the valve's moving parts.

And of course a seized compressor would be expected to trip the circuit breaker the next time it tries to turn on. The TEV didn't cause a short circuit but it could have damaged the compressor leading to an overcurrent and a tripped circuit breaker.

Is there some way to check the thermostatic expansion valve?

Any idea on how to check / diagnose the TXV (TEV)? 2011-08-07 by TN-Goose

By (mod) - Tip for Checking the TEV:

Checking the TEV:

A simple step that can tell something about the TEV (TXV in your lingo) is to just try warming it up with a hand or a hair blow-dryer.

If the valve is frozen and it's warmed it'll start working.

Watch out: however this is not a complete test. For example a TXV that is mis-adjusted or that is debris clogged won't respond to simple heating.

Other tests involve using a gauge set and making adjustments to the valve while watching the frost line on the cooling coil. On occasion we might hear chattering at the TEV - an indication it's not working properly.