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gotoman for ac
gotoman for ac, HVAC Technician
Category: HVAC
Satisfied Customers: 5163
Experience:  51 years of experience install design and repair of all makes and models of AC
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my air conditioning compressor wont shut off even when thermostat

Customer Question

my air conditioning compressor won't shut off even when thermostat is disconnected
Submitted: 6 years ago.
Category: HVAC
Expert:  gotoman for ac replied 6 years ago.
Chat Conversation Started
gotoman for ac :

Sounds like you have welded contactor. Open access panel and check contactor. Kill power to all equipment. See if comtactor stays energized. Russ

JACUSTOMER-t2lt7rle- :

i pulled the contactor, unit shot off, but turned back on when i put it back in

gotoman for ac :

Are the contacts welded shut. Russ

JACUSTOMER-t2lt7rle- :

by contactor, i'm assuming you mean the box outside the house that contains the black plastic square with a handle that pulls out and has 4 metal contacts on it

JACUSTOMER-t2lt7rle- :

i went outside, opened the access door and pulled out the black plastic unit by the handle and the unit shut off, but it went back on when i reattached it

gotoman for ac :

No that is a disconnect. The contactor is the two pole relay located in outside unit. Main power comes in bottom of contactor is energized by thermostat and puts power to compressor and fan, Russ

JACUSTOMER-t2lt7rle- :

so i have to take off the entire housing to the unit?

gotoman for ac :

No just access panel. Two to four screws . Russ

JACUSTOMER-t2lt7rle- :

on side of unit where condendor is facing?

gotoman for ac :

Find where power goes into unit. Panel will be on corner or side of unit. Russ

JACUSTOMER-t2lt7rle- :

ok be back in a few minutes thans

gotoman for ac :

No problem. Russ

JACUSTOMER-t2lt7rle- :

got the access door off russ. now what?

gotoman for ac :

Good. You will see where main power comes into a relay. Rhe middle of relay move up and down to open and close contacts. Check the middle of contactor to see if pulled down and copper contacts are black are burny. Russ

JACUSTOMER-t2lt7rle- :

didn't see anything burnt. (there was an old dead mouse in there though)

gotoman for ac :

With poer off see if you can moce center of contactor up and down. Russ

JACUSTOMER-t2lt7rle- :

slide up and down?

gotoman for ac :

Push in on middle of contactor.

JACUSTOMER-t2lt7rle- :

i did and it popped away from the contacts

JACUSTOMER-t2lt7rle- :

it's spring loaded and stays open (away from the contacts) when i push on it

gotoman for ac :

Turn power on inside and watch contactor. See if it pull in. Russ

JACUSTOMER-t2lt7rle- :

it pulled in and went on russ!!

gotoman for ac :

There is a yellow wire at outside unit disconnect it. Russ

JACUSTOMER-t2lt7rle- :

do i do this while the unit is running? or turn off?

gotoman for ac :

While it is running. Small thermostat wire. Russ

JACUSTOMER-t2lt7rle- :

is it the one that plugs in by the connector?

gotoman for ac :

No you have a group of thermostat wires coming into unit Red,Yellow,White ect. Just disconnect yellow wire. You can turn of power to outside unit for safety. Russ

JACUSTOMER-t2lt7rle- :

there are 3 yellow wires that are plugged in to a seperate box with the red, yellow, etc. next to but not part of the connector. how do i know which yellow wire to unplug russ?

JACUSTOMER-t2lt7rle- :

the three yellow wires are plugged in vertically one on top of the other . 2 look like they are plugged into the same connection and the other below it. the only other wire connected to that small box is black

gotoman for ac :

You have a problem with the communicating circiut. You will need to call a service tech with proper instruments to check system. I work on these systems everyday and this is more than can be handled over the internet. Russ

JACUSTOMER-t2lt7rle- :

can I run the unit until I get a serviceman out?

JACUSTOMER-t2lt7rle- :

it seems to be running fine now. cool air coming into the house

gotoman for ac :

Yes as long as it is cooling not heating. Russ

JACUSTOMER-t2lt7rle- :

im assuming you mean to shut it down if warm air starts coming thru the air conditioning system instead of cold. this would have nothing to do with the heating system of the house right? it's only about the A/C. is this something that needs checking soon?

gotoman for ac :

No Just wanted to make sure you were cooling. Nothing to check just call tech and try to stay cool. Russ

JACUSTOMER-t2lt7rle- :

thank you, russ

gotoman for ac and 3 other HVAC Specialists are ready to help you
Expert:  gotoman for ac replied 6 years ago.
Your welcome. sorry we could not go further. Russ