Storm Damage or Weather Impact on A/C or Heat Pump FAQs

Diagnose storm damaged compressor/condenser
Effects of very hot weather on A/C or Heat Pump Operation

Storm Damage to A/C & Heat Pump Systems FAQs

Storm damage to outdoor compressor/condenser unit

I have a Payne 3.5 ton unit on my house. It was replaced about 3 years ago. L

ast year we had a severe electrical storm and immediately after I noticed that the unit runs all day and does not cool well.

A service tech says that everything looks fine but he replaced the compressor anyway and the unit began to cool better.

This year it has done the same thing after a storm but the company will not replace the compressor because the gauges show it is working.

How can this be? by Dennis

by (mod) - start with proper and clear diagnostic tests

Dennis,

A number of problems could cause an air conditioner to not cool so well - low refrigerant for example.

If your tech replaced the compressor he would have had a reason, such as damage from the electrical storm, since that is quite an expensive repair.

Or the first time it was under warranty and profited the contractor but the second time it's not under warranty.

But you and I can't know that the two cases are identical with so little diagnostic data.

First it would be appropriate to correctly diagnose the cause of poor cooling - it could be something trivial like a dirty air filter, or it could be moisture or dirt interfering with a thermostatic expansion valve, or if the electrical storm actually damaged the equpment, perhaps a control circuit board.

by Dennis - It was storm damage

Sorry, i guess i wasn't clear. My unit was running and cooling well before we had a storm.

After the storm it is still running and cooling, but not as well. All the normal checks and issues have been checked and the tech even says the refrigerant and pressures show normal, the filters are new, coils are clean and remember almost immediately after the storm brownout it lost cooling power.

Even though the tech says everything looks fine (pressures, voltages, filters, coolant, etc) it is just not putting out air as cold as it was, showing about a 13 degree drop between inlet and outlet temperatures. The compressor is cycling but it just acts like it is not cooling enough. Anyway, thanks for the help.

by (mod) - rotation speeds of cooling fans, amperage draw of the compressor, and system refrigerant pressures

Dennis, did the diagnostic steps confirm rotation speeds of cooling fans, amperage draw of the compressor, and system refrigerant pressures? A bad capacitor or control board that causes a fan to run backwards or slowly could perhaps be involved.

HVAC Troubleshooting, Hot Weather-Related FAQs

Texas A/C unit stops working in hottest part of the day

Here recently, my heat pump unit has started to act up. It tends to work well for the better part of the day.

The compressor will run and there is good cold air flow out of the supply registers. However, late in the afternoon (peak heat time) the heat pump fan will abruptly stop (with great deal of heat near heat pump fan).

Restarting the system after a 30-45 minute "off" cycle will generally restore its operation. Any ideas? - by dh in texas

Photo: InspectApedia reader Rick built this shade over his compressor-condenser unit but

Watch out: insufficient air space between the compressor's top fan outlet and the roof underside can increase the operating temperature and cost and shorten the life of this unit. Check the IO manual for your compressor/condenser unit for clearance distance requirements.

See CLEARANCE DISTANCE, HVAC

and AIR CONDITIONER COVER USE

Reply by (mod) - heat pump that works ok in cooling mode until late in the day when it shuts off

DH:

Your description of a heat pump that works ok in cooling mode until late in the day when it shuts off and is very hot makes me think that a motor, possibly the fan motor is overheating and shutting down on thermal reset.

Some electric motors contain a built-in thermal overload switch that will reset itself automatically when the motor cools down.

If that's what is happening the motor could need replacement, or it may be that the compressor is in a very hot location and / or is not seeing adequate air flow.

I see this problem when a compressor unit is installed too close to a building or when airflow in or out of the unit is blocked by a building wall or shrubbery.

It's worth a service call to have a trained tech look at the installation and motor. Let us know what you find - it will help other readers.

If the system is actually running but air flow becomes weak, that's a different problem: probably an ice or frost blocked cooling coil in the air handler.

100 degree Weather: Outside condenser unit only runs for 15 minutes unless I turn it off to cool down

My outside unit turns on and will run for about 15 minutes and then stops.

I let it cool down for a while and it will work again but only for 15 minutes.

I live in georgia and its been 100+ degrees here for a week or more. any info would be great. by mike

Reply by (mod) - "test" for an overheating compressor/condenser unit by wetting down that outside component with a garden hose,

Mike:

people "test" for an overheating compressor/condenser unit by wetting down that outside component with a garden hose, on the premise that the system is designed to be exposed to rainfall without damage. But if the unit is overheating I'd check for

- blockage of air flow by location too close to a building wall or fence or shrubs
- dirt or debris inside the condenser unit
- dust and debris on the condenser coil fins (big payback from keeping the coil clean)

and last and worst
- a failing, overheating compressor motor that is drawing high amps.

TN-Goose: specifying voltage levels and wiring for individual control circuit boards is, sorry to say, beyond my competence and scope of such a general discussion. Other than checking for normal voltage levels (120V or 240V or 24V depending on the component), more detailed control circuit analysis surely depends on the air conditioner model.

In my experience, (and what Hilliard taught at A/C school) most electrical problems on A/C systems are in compressors, relays, and overloads.

by dee

mike- sounds like compressor overload, most units can be replaced- the overload is generaly under 50 bucks.

by (mod) - electric motor overload switch that automatically shuts off the system

Thanks Dee.

Mike: Dee is referring to an electric motor overload switch that automatically shuts off the system - more often found on fan motors at the compressor/condenser unit or in the air handler blower compartment on that fan.

On many A/C compressors and some other electric motors such as well pumps, there is an internal overload switch that will reset itself automatically once the unit cools down.

A bad overload switch (if there is a replaceable unit) may be worth a try but more often in my experience if a motor keeps tripping on overload there is a more basic problem at work causing that overheating.

Hot Weather Compressor Failure: pressure readings mean that a compressor motor is bad?

I have two heat pumps on the property that i work at. Outside air temp. has been about 95 degrees, The high side pressure is about 190 to 200 psig & the low side is about 110 to 120 or higher.

I have already replaced the compressor on another unit doing tha same thing.

Before i replace these two i just wanted a second opinion that it is the compressor that is going bad. On 2011-07-14 by PatrickBumgarner

by (mod) - check the TEV and other causes for abnormal refrigerant pressures before replacing a compressor motor

Patrick: I wouldn't replace a compressor unit just based on those pressure readings, as other controls could be at fault such as a thermostatic expansion valve;

also at very high outdoor temps the compressor/condenser may just not be keeping up. A diagnosis of bad A/C compressor would look not just at its output pressure but also the amps it's drawing.

Finally, high pressure on the LOW side after the compressor has been running for a while would certainly make it worth looking at that refrigerant metering device.