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Photograph of the outdoor safety switch for an air conditioning residential systemAir Conditioning & Heat Pump Control & Switche FAQs

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HVAC system control & switch Questions & Answers:

This article series explains where to find and how to use the switches and controls for air conditioning and heat pump systems.



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Air Conditioner Switch & Control FAQs

A/C Compressor control board (C) D FriedmanMost recent to older

On 2017-01-13 00:33:26.160441 by (mod)

John

Thanks for the follow-up; do let me know what happens as what you learn will help other readers too.

On 2017-01-12 23:57:02.362022 by John

Thanks for the info I have searched every where for this part and no luck. Though there are some web sites that say they have it but further investigation the companies are scams take your money and run I will give Frank Switzer a call. I found a company Baytronics who said he might be able to repair the circuit board #03101212700
that appaers to be my only hope at this point if Frank does not have a solution. Still can't believe York would screw their customers like that. Will never buy a York product of any kind again

On 2017-01-10 16:08:16.943943 by (mod)

John

Yeah I am troubled by this sort of problem too - a component fails and nobody provides a replacement, forcing you to replace a much larger assembly or even an entire device.

A problem is that nobody wants to accept the very serious safety/fire/injury liability of promising you that it's ok to in essence modify a manufacturer's original design.

Another problem is that the number of people who can work on and repair old circuit boards has dwindled to almost nobody. I recently spoke with the company who purchased Sonic Frontiers, a manufacturer of excellent tube amplifiers, to discuss possible repair of a bad circuit board in that amp. The technician at the new owner burst out laughing. "A TUBE amplifier?", he guffawed. "We don't have anybody here who even knows what that is."

On rare occasions you might find a local electrical engineer hobbyist who is interested in trying to fix an old circuit board but it's doubtful.

Sorry. If York isn't going to offer help and if you can't find a used but working board to replace the control module in your heat pump you're sunk.

But before giving up, do some online searching for "York Heat Pump Replacement Circuit Boards" - you'll find several vendors who say they have parts.

Give a call to
Frank Switzer Owner and HVAC Technician

715-839-0934
Toll Free 1-877-839-5565
Air Dynamics Heating & Cooling, LLC
The Heating and Cooling Warehouse
1501 Nicholas Dr. Eau Claire, WI 54703

As he lists several replacement control module boards for York HVAC equipment, one of which might work for you. You can tell him we sent you but note that InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information provided free to the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website.

Watch out: some HVAC parts vendors WASTE YOUR TIME by listing at their website lines like "Replacement for York Circuit Board 03101212700" but when you actually look at the vendor's web page for that part they thumb their electronic nose, saying "Obsolete part, no longer available" - which makes me wonder why they listed it.

On 2017-01-10 12:08:19.092765 by john

I have a York heat pump the control module #03101212700 (circuit board) the is bad unfortunately York stopped making the part in 2010 no replacement. Question has any one found a bard they could wire in o make the air handler work. The board controls the blower and heat strips during heat cycle and blower during AC cycle. wWithout this part te whole system will have to be replaced for $150 part

On 2016-12-10 14:22:10.201088 by CJ

I recently replaced my thermostat on a heat pump system to a Honeywell RTH7500D. The wiring was slightly different from the old analog TT to the new one. I successfully got the A/C working, but the heat comes on for about 30 secs to a minute, then I see 'Aux' pop up on the display for a second and the system immediately goes into 'Wait.' I am assuming it is trying to activate Aux Heat, fails, and drops into 'Wait' to prevent damage to the system. I don't know if the problem is wiring or programming in the thermostat. As far as I know, it worked fine on the old thermostat.

Here is how I wired it, based off how I interpreted the instruction manual:
Wire Color --> Old TT --> New TT
Blue --> B --> C
Yellow --> Y --> Y
Green --> G --> G
Red --> R --> R
Tan --> X1 --> E
Orange --> O --> O
White --> Wasn't used in old TT

Thanks.

On 2016-12-03 22:42:55.428075 by Brian

My unit works fine on a/c, but when I try to turn on the heat I get nothing.

On 2016-12-02 00:47:36.509264 by Anonymous

bought an older home with a daikain ducted air conditioner installed and under the control unit is a switch panel. Don't know how to use this

On 2016-11-20 22:10:00.720798 by Johnny 5

20 year old Vexar heat pump, outside unit won't come on.
I can hear the relay clicking like it's trying, but nothing happens.

Could it be bad contacts on the relay? Or bad motor start caps.
They are both pretty rusty, but not bulging or leaking...

On 2016-05-14 19:21:35.361847 by (mod)

Typically there are relays in the compressor/condenser unit and often in the air handler box as well. That's a service item for your trained service tech, not a homeowner replacement part.

On 2016-05-14 17:57:27.151458 by Tom

I have central air conditioning . and heat.. Heat works air conditioning don't. I have been told it could be relay switch. Where is relay location

On 2016-03-13 04:01:23.740221 by (mod)

Arm yourself with the model and serial numbers and you should be able to download an owner's manual with codes for your unit at no cost. Without that data, as we replied by email, we're left in a fog.

On 2016-03-12 03:50:43.915704 by Jason FRANKLIN

I have a Emerson comfort diagnostic key on my single faze ac condensing unit that has a green red an yellow light on it the yellow light flashes 6 times what does that mean I've tried looking on the internet for the codes but can't find them can you help?

On 2016-02-23 14:37:04.420947 by shellyneedshelp

Thanks for replying. Seems to be working again now.

On 2016-02-22 21:50:47.262050 by (mod)

Shelly

If you system is a heat pump it may be that it's too cold outside for it to function AND your backup heat is not working. I'd call for repair.

On 2016-02-22 15:38:37.344010 by shellyneedshelp

Hi, Turned the HVAC to "fan" yesterday just to circulate air in the house. Thermostat setting was On for Fan and Off for System. When I tried to switch back to heat last night, no warmth and couldn't get fan to cut off even when Fan set to Auto and System to Off. Turned HVAC off at breaker box for several hours. Turned breakers back on this morning, Fan to Auto and System to Heat (started in Off, switched to heat after breakers turned on). Blower comes on but no heat. Tried moving temp switch up and down, no effect. Any ideas please?

On 2016-01-21 21:27:47.026667 by (mod)

Check for a loose or damaged blower fan

On 2016-01-21 20:40:12.150249 by joannabanana127

my carrier home heat pump is clicking rapidly nonstop while in heat mode at copressor but still heats can you help

On 2015-11-06 20:03:55.799185 by (mod)

Is your system running in backup heat mode? if so that's normal.

On 2015-11-05 15:58:20.215523 by Doumbia

Hi, my outside unit fan does not turn on but i do have heat coming through the vent and the green comes on the thermostat.

On 2015-08-14 16:55:44.772592 by (mod)

KEvin I would turn the system off to reduce further damage pending repair. Given the A/C brand and model one would find the owner's manual to translate the diagnostic code given by the dual red lights.

On 2015-08-13 06:52:51.518066 by Kevin

outside unit fan running very slow turned power off and theres a dual red light blinking

On 2015-07-17 20:07:37.398971 by (mod)

Danny

The LG Portable Air Conditioner you cite uses a remote control for its operations. If you've lost your remote or need a user's guide, contact LG:

LG Electronics U.S.A., Inc.
1000 Sylvan Avenue Englewood Cliffs, NJ 07632 Customer Service and Technical Support: (800) 243-0000
LG.com

On 2015-07-14 16:26:18.894349 by Anonymous

JRB

It sounds as if your AC circuit is drawing excess current - something is failing, probably a motor. Watch out: don't keep running it or you risk as fire.

On 2015-07-11 14:17:18.548370 by DANNY

CANNOT LOCATE CUTOFF SWITCH ON LG MODEL LP1414GXR?

On 2015-06-27 14:53:56.098700 by JRB

My air conditioner runs great but the circuit breaker keeps clicking off. It may run for several hours before clicking off and usually I trip the switch and it comes back on, however every now and then when I click the breaker back on it fails to work. Once waiting a several minutes it starts again when I click the switch. I replaced the circuit breaker but it did not fix the problem. I have blown out the radiator coils so it is not blocking air flow. I am at a loss. I have replaced the filter. I would appreciate any suggestions. JR

On 2015-06-17 20:38:28.255590 by (mod)

Jay the service tech, in addition to checking for a bad control or relay or board or wiring, will perhaps check the current draw to look for a seized motor.

On 2015-06-16 17:14:01.572850 by Jay

Hi there,
Thank for your informative post. I Have a Kenmore AC unit outside, the fan runs slow and compressor doesnt turn on. I replaced the capacitor and the compressor still doesnt work. Any tips would be greatly appreciated

On 2015-06-14 20:13:17.915790 by (mod)

ANON

try the diagnostics beginning with the article linked-to above named

COMPRESSOR CONDENSER: problems with air conditioner compressor/condenser units

On 2015-06-14 14:51:30.901070 by Anonymous

My blower comes on but split unit outside does not. I have replaced capacitor. I can manually push in something that looks like a breaker in side unit (below and to the right of capacitor) and unit will come on as long as I hold it in.

On 2015-06-10 23:36:11.442910 by Anonymous

Thank You for the feed back Dan it was very helpful

On 2015-06-09 18:37:10.812170 by (mod)

Mike

If the unit is switching to heating mode I suspect a control board or heater element failure.

A failing compressor motor will also trip the breaker.

On 2015-06-09 17:41:26.501790 by Mike

I have an air to air heat pump that pops the breaker in the cord when changing thermostat the heat.The system works fine in cooling mode when removing the unit from the wall the 4 way valve made some strange noise . Is the power draw on the 4 way valve strong enough to pop the breaker?

On 2015-06-06 12:53:45.540180 by (mod)

Kevin

Techs do this as a test and only BRIEFLY.

I would never force equipment to run by holding a relay closed - doing so risks overheating a control or component and thus a fire or other damage.

On 2015-06-06 12:52:44.722650 by (mod)

RE posted from mobile site

AUTHOR:Kevin klinglesmith (no email)

COMMENT:Will it hurt the unit if I force the spring loaded switch together and let the unit run

On 2015-05-12 20:57:58.406430 by (mod)

Aha
so let's take a look: did he

- bang into something
- spill anything
- turn any switches on or off
- disconnect anything

As a simple example: if your AC system has a condensate drain pan safety switch that was disturbed, that alone could have switched off the AC unit.


On 2015-05-12 20:39:30.198260 by Laura

The plumber did go into the attic and told me that he would be vacuuming/cleaning out the drain from the a/c that drains to the sink. And being from Texas we do use a/c mostly year round. The a/c will not work at all.

On 2015-05-12 20:32:16.724980 by Anonymous

The plumber went into the attic and used the vacuum to clean out the overflow pipe that comes out of the a/c. And we use our a/c year round in the south! ha

On 2015-05-12 20:28:34.209280 by (mod)

Laura

I don't blame you for being baffled. I call this "the last person in" syndrome. Service techs know that the last person to touch the equipment will be held responsible for its next failure. Sometimes justly, sometimes not. In this case, if the plumber never touched the A/C system, just the sink drain, I would not think she or he had a thing to do with the air conditioning system.

Possibly the fault showed up because the system began to get used?

Details?

On 2015-05-12 20:25:49.712490 by Laura

The plumber came and cleaned out a drain from the a/c that runs into one of my sinks because the sink was clogging up. Now my a/c doesn't work at all and it was fine the same day of him doing that. Now an a/c man tells me that is the circuit board needing to be replaced!

 

Question: safety switch

(Feb 9, 2014) takka9927@yahoo.com.au said:

ducted gas heating triggers safety switch

Reply:

We'd like to help but don't understand the questio. Which safety switch?

Question: air conditioner trips circuit breaker

(May 10, 2014) William said:

air conditioner wont run it will kick the house breaker out when you turn the power on

Reply:

William, leave the unit off. The problem could be a bad compressor - we don't want to damage other components or overheat wiring (a fire hazard) by trying to run it.

Question: Air conditioner / heat pump won't turn on

(May 30, 2014) Hi, I'm Georgia, my goodman all in one heat pump will not come on at all . We put in new thermostat and it shut whole system down, we replaced transformer, 2 capacitors and contactor it did not help. Nothen comes on. Can someone help.? said:

Hi, I'm Georgia, my goodman all in one heat pump will not come on at all . We put in new thermostat and it shut whole system down, we replaced transformer, 2 capacitors and contactor it did not help. Nothen comes on. Can someone help.?capacitors and contactor it did not help. Nothen comes on. Can someone help.? I hope I'm put this in right place don't see anywhere else. Thanks

(June 4, 2014) Namecarhy said:

outside unit does wrk plz help

Reply:

A good place to start diagnosis of inoperative heat pumps is right at LOST COOLING CAPACITY where we give a list of steps to take

Question: air conditioner keeps cooling even in heating mode

(June 24, 2014) justice dithole said:

hi I have a problem with window type air conditioner, it is cooling even when I have turned the adjuster to heating mode. it only cools and regrets to warm me up in my office

Reply:

(June 24, 2014) DAVE said: What does it do Justice?

Justice,

Dave and I face the difficulty of guessing at what's wrong on an air conditioner with very little information. But I'll add that if a unit will not change from cooling to heating mode, and presuming it is designed as a heat pump capable of both cooling and heating, then an internal control or switch needs repair or replacement - possibly the reversing valve in the unit.

See REVERSING VALVE on HEAT PUMPS

Question: air conditioner fails in bad weather

(June 28, 2014) terry wycoff said:

i have an old arcla? brand ac that runs water outside,but as soon as you turn the dial only runs seconds

(July 28, 2014) Anonymous said:

Hi. I have brand new American Standard split system. Runs fine until there's a storm. Power doesn't need to go off, nothing weird happens in the house, but the unit loses all power, even the thermostat is dead, which is wired to the air handler in the crawl space. I've had utlility company out and everything on their side is good. I've had electrician out and all on my side is good. Unit is under warranty for now, but I'm frustrated.

I have to call them out on average once a month when a storm goes through. I have two other places and this doesn't happen, ever. Was thinking about installing whole house surge protector, but both air guy and electrician tell me that won't help my problem. This is not good and I need some type of idea on what to do. I'm really upset, since my air company can't seem to fix it. Thank you.

Reply:

I agree you need better diagnosis, and from here can only guess.

Has anyone checked for a water or moisture problem in controls or wiring?

Question: American Standard Heritage 16 Heat pump operating trouble

8/18/14 sleepless in Seattle cause no cooling said:

I have an American Standard Heritage 16 Heat pump. I did the terrible deed of not cleaning the air filter located above furnace and it shut off the whole system. I cleaned the filter and ran through some test modes on the thermostat and the furnace comes on fine, but not the heat pump. I read that a motor may have a reset button that needs attention, but I opened up the side of this thing and it looks like a motor covered with orange insulation is under the fan, but I can't see how to get to it. Yes. I know nothing about this stuff but can read directions, only I'm not able to get any schematics on this thing. Any help would be appreciated.

Reply:

Sleepless - Seattle

We're flying blind here but possibly a fan motor might overheat due to reduced air flow. However If the furnace and blower run in response to a call for heat then the fan motor is working. If the fan is inoperative the furnace limit control should shut the system down.

I'm not sure how an indoor fan problem will keep an outdoor heat pump from turning on. I'd look for a thermostat mode setting problem or a control board or relay problem first.

Reader follow-up:

The furnace fan comes on during test mode from the thermostat. Once the thermostat calls for heat or cooling, it shuts off and heat pump does not come on. Thermostat flashes "wait" like the heat pump is in some setup or testing mode?

Reply:

If the blower runs properly in test mode then we're not looking at a problem with the blower fan motor itself. More likely there is a problem with the compressor/condenser unit or a control board, relay, or theremostat problem.

First check your thermostat's instructions and manual. Some therm air conditioner and heat pump thermostats such as some Honeywell models will introduce a five-minute delay before starting the compressor when the thermostat is switched "on" or set higher in short intervals. That's because rapid turning off and on of a call for heat at a thermostat can cause compressor motor short cycling. Because some compressors may have trouble starting against high refrigerant head pressures that remain at the moment of switching "off" the five minute delay is intended to give time for refrigerant pressures to equalize in the system - giving an easier start to the compressor. If the compressor still won't start I'd suspect a bad start relay or start capacitor.

It's time to ask your HVAC service company to send out a trained service tech.

Question: furnace fan comes on in thermostat test mode - flashing "Wait"

(Aug 19, 2014) Sleepless in Seattle said:
Sleepless in San Miguel
The furnace fan comes on during test mode from the thermostat. Once the thermostat calls for heat or cooling, it shuts off and heat pump does not come on. Thermostat flashes "wait" like the heat pump is in some setup or testing mode?

Reply:

If the blower runs properly in test mode then we're not looking at a problem with the blower fan motor itself. More likely there is a problem with the compressor/condenser unit or a control board, relay, or theremostat problem.

First check your thermostat's instructions and manual. Some therm air conditioner and heat pump thermostats such as some Honeywell models will introduce a five-minute delay before starting the compressor when the thermostat is switched "on" or set higher in short intervals. That's because rapid turning off and on of a call for heat at a thermostat can cause compressor motor short cycling. Because some compressors may have trouble starting against high refrigerant head pressures that remain at the moment of switching "off" the five minute delay is intended to give time for refrigerant pressures to equalize in the system - giving an easier start to the compressor. If the compressor still won't start I'd suspect a bad start relay or start capacitor.

(Aug 19, 2014) Sleepless - Seattle said:
Service tech said the thermostat (Honeywell) is bad, but still under warranty. Yay!
Thanks for your help.

Question: service panel got wet, mother board got wet, green light not working

(Aug 20, 2014) bov said:
I left my service panel off and the inside of it got wet. The mother board had a green light that is not working. The unit does not come on at all. What should I do about it to fix it.

Reply:

Bov I'm troubled by the water damage too and can't begin to tell you how to fix it - knowing nothing about your system, what it is, what got wet, or what are your skills. There is risk of further equipment damage just from turning it on if the controls got wet. I'd ask for help from an experienced service tech or electrician both for safety and to avoid frying more components or getting shocked.

Question: repair advice

(Sept 17, 2014) jimsworlds@wildblue.net said:
I have amid70's rudd heat pump and the manufactrs model has long

(Sept 17, 2014) jimsworld@wildblue.net said:
I have a rudd heat pump from the mid 70s and the model # has long since faded does any one know how to identify? i need a schematic BAD! It stopped coming on I suspect the tranformer low voltage [it is reading 21v] but I need schematic to check other switches

(Jan 4, 2015) Al T. said:
I have an American Standard packaged heat pump model WCY . In heat mode all works well except in the early morning hours when the outside temp is in the low 30's. I get cool air blowing instead of heat. the only way to get heated air is to turn off unit and turn it on in cooling mode for 10 min. Then turn unit off and then turn it back on in heat mode. it then works fine until next morning when the outside temp is in the low 30's again. Need repair advice.

Reply:

AI

Have you checked for a frost-clogged condensing coil outside or for the system's backup heat not working or a defrost cycle not working?

(Jan 9, 2015) Al T. said:
Dan, There is frost on the outside condensing. The system does not have a backup electric heater. I suspect that the defrost cycle is not working. The indoor blower just blows cold air until I manually reverse cycle to cool then to hot.

Replyl:

That's a reasonable guess. You may be able to replace a control board or relay, but if there is a heater element on the compressor or elsewhere in the unit it'd make sense to check the heater element itself to be sure it works - else it needs to be replaced.

Question: Florida Heat Pump - not working in heating mode

(Feb 5, 2015) T.P. said:
Hey folks, I've got a well used Florida Heat Pump. During the winter, about 4 times/week, the air suddenly blows cold. We found that stopping the heat (on the thermostat), and restarting it seems to "reset" the system, and after a few minutes delay, it returns to normal temps. Any idea what might be going on? Thanks.

Reply:

Sounds as if your heat pump is not heating: perhaps the thermostatic expansion valve is freezing-up. Less likely, a control board or relay problem. Ask your service tech to check out the system. Keep us posted.

Question: Comfortmaker blower coil electrical unit not cooling

17 March 2015 tamie said:
HI, I have a cofortmaker blower coil electrical unit. I had this unit installed in 2010. I had to replace a bad txv sensor module on this unit in 2013. My AC unit keeps running. both inside/outside units & the air that is coming from vents is not very cool during the day. Looking for some answers, Before I call the tech.

Reply:

Tamie

Not cooling - may be due to lost refrigerant, if all of the other components including the compressor are running. If that turns out to be the case, I would not be happy with simply having refrigerant added. The leak should be found and fixed.

Article Series Contents

If your air conditioning or heat pump system has lost its cooling capacity or won't start select one or more of the diagnostic articles listed below.

...


Continue reading at CONTROLS & SWITCHES, A/C - HEAT PUMP or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES.

Or see ELECTRICAL POWER SWITCH FOR HEAT

Or see CAPILLARY TUBES

The main operating controls for HVAC systems and their functions are are discussed
at OPERATING CONTROLS, A/C & HEAT PUMP where you will find a discussion of thermostats, zone dampers, and circuit breakers on air conditioners and heat pump systems.

Other air conditioning and heat pump diagnostic procedures are
at LOST COOLING CAPACITY.

Suggested citation for this web page

A/C HEAT PUMP CONTROL / SWITCH FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

INDEX to RELATED ARTICLES: ARTICLE INDEX to AIR CONDITIONING & HEAT PUMPS

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