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I have an Amana AC/Heating wall unit, PTH153A50AA. It's served us well but now it intermittedly stops working. When we turn it to "FAN" it will always work, but as soon as we turn it to anything else, it switches off. Then, out of the blue, it kicks on. It may work for days, hours, mins, or a split second before it shutsoff again. You can hear it click sometimes, but doesn't come on. Inside or outsided temperature doesn't seem to make a difference. What's happening? Is this something I can fix or do I need a qualified repairman? Thanks!!

Submitted: 325 days and 1 hours ago.

Category: HVAC

Value: $9

Status: AWAITING EXPERT REPLY

Posted by Doug Eby 324 days and 19 hours ago.

Answer

Hi there. I would recommend getting a service tech. Intermittent problems like this are usually electronic. It may be difficult for the tech to diagnose unless it happens while he's there. Sounds like the control board is going bad, but it's expensive to just start replacing parts at random.

324 days and 18 hours ago.

Reply

I was hoping for more technical breakdown of possible problems. If I'm getting the fan on every time, and all other choices choices on the contact switch is is intermittent, I can rule out the switch being the problem. I get a definite sound of a relay clicking. The A/C can sit in the on position for days and out of the blue, just click on. This doesn't point to any specific part failure? If not, is it routine for a tech to change out the entire board (if this is the problem) to this unit or can I expect an actual component repair?

Accepted Answer

Ok. My understanding of the problem is when you put the thermostsat to fan, the fan comes on. But if you switch to heat or a/c it does nothing. If it's left on a/c or heat, it may come on by itself intermittently. If you open the t-stat, there will be several multicolored wires inside.The t-stat normally works on 24VAC. You should check the voltage between 'R' and 'C' to verify. If no wire is connected to 'C' then check any other terminal with a wire connected. Disconnect the wire at the 'R' terminal to prevent damage to the t-stat. Then connect a jumper wire from this wire to the 'G' and the 'W'. This should start the indoor fan & heat sequence. Then remove the jumper from the 'W' & connect to the 'Y'. The a/c should come on. If the system responds normally to this, then the problem is in the t-stat. If the system is not responding or acts intermittently as before, then I would suspect the control board. I wouldn't suspect an individual relay since you're having trouble with the a/c and heat. If the control board is defective, you may need to contact a service tech to replace since I don't believe that you would be able to purchase one on your own. Most a/c companies will only sell to contractors. The t-stat you can get from a hardware store.
I hope this helps.
Doug

Accepts:
Expert:	Doug Eby
Pos. Feedback:	100.0 %
Answered:	1/2/2009

HVAC Technician

15 Years Navy, commercial, restaurant

324 days and 10 hours ago.

Reply

Thanks for the info. This was informative.

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Hi there. I would recommend getting a service tech. Intermittent problems like this are usually electronic. It may be difficult for the tech to diagnose unless it happens while he's there. Sounds like the control board is going bad, but it's expensive to just start replacing parts at random.

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Accepted Answer

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Thanks for the info. This was informative.

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