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airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8131
Experience:  Furnace, A/C and heat pump specialist.
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Honeywell Thermostat does not turn off AC and pipes are

Customer Question

Honeywell Thermostat does not turn off AC and pipes are freezing. Even removing Tstat from wall does not shut AC off.
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.

Most common cause is burned contactors in outdoor unit.Ants may fry causing the contacts to stick closed allowing outdoor to run non stop. Can you do some hands on troubleshooting and do you have a multi meter?

Customer: replied 1 year ago.
No multi-meter, troubleshooting yes
Expert:  airheatman replied 1 year ago.

In outdoor unit there is a relay called a contactor. They have 230 volts supplying power any time breaker is on. When thermostat calls for AC, it sends 24 volts to the coil on this contactor engaging the contactor and allowing the 230 volts to flow through to outdoor fan and compressor.

If they burn and stick together the voltage continues to flow even when thermostat is satisfied or shut off which causes icing because e indoor blower has stopped.

Open the service panel on outdoor unit and take a look at these contactor and see if they are burned.

http://i.imgur.com/pT2mWjq.png

Customer: replied 1 year ago.
I need to purchase new contactors and install ? It's too dark to check now.
Expert:  airheatman replied 1 year ago.

If they are burned ands stuck together yes. Simple to replace and cost about 20 bucks at any appliance parts store.

Customer: replied 1 year ago.
if I call you I get charged another $24 on top of the $32 ?
Expert:  airheatman replied 1 year ago.

Yes, the phone call is an auto offer by the website. It is optional. We can continue here texting without the call.

Customer: replied 1 year ago.
Well the AC is running now and getting cool air, to turn off i need to go to circuit breaker. I had off for 4 hours today trying to defrost. When i pull the tstat off the wall AC runs but fan goes off.
Expert:  airheatman replied 1 year ago.

That is correct.If you allowed coil to thaw, the outdoor can run without icing as long as blower is running inside. Just when thermostat reaches setpoint, turn off breaker to outside when the indoor fan cycles off until you replace the contactor.

Customer: replied 1 year ago.
ok thanks, ***** ***** check contactors in the day light tomorrow. I thought Tstat was broken.
Expert:  airheatman replied 1 year ago.

Let me know what you find.

Customer: replied 1 year ago.
would you have a better pic of what they look like ?
Customer: replied 1 year ago.
how long will this problem stay open ?
Expert:  airheatman replied 1 year ago.
Expert:  airheatman replied 1 year ago.

After leaving a rating of 3 or higher, you can come back to question for 30 days with no additional fee.

Customer: replied 1 year ago.
Hi, I took contractor out of AC and it does look burned. Part number is ***** Doesn't seem to be available in any local stores and requires online ordering. Do you know where this part is sold in 80134 area code ?
Customer: replied 1 year ago.
I meant contactor
Expert:  airheatman replied 1 year ago.

Do you know where Appliance Factory Parts is located?

Expert:  airheatman replied 1 year ago.

Never mind, they do not have them.I called. Let me see what I can find

Expert:  airheatman replied 1 year ago.

Do you have any type of appliance parts store nearby.Most any of them should carry this.

You do not have to have that particular part number.A generic contactor will work.Just tell them you need a set of 30VA 230 volt ac contactors with a 24 volt coil.

Customer: replied 1 year ago.
Home Depot and Lowes are near by. But I'm afraid a generic will not fit properly into AC slot on provided.
Expert:  airheatman replied 1 year ago.

They can be mounted using a couple of drill point screws if necessary as long as no wires are near the metal cabinet.Otherwise you may have to either order online or call a local contractor who will have them in stock, but that will of course be more costly as he will want a service call to install them.

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