Home AC question

My outside (condenser) unit has stopped working. The contactor was replaced about a month ago (with a unit that looked completely different) and the unit worked for a couple of weeks, then stopped. When the AC guys came, it turned right on.

Well, it quit working again Monday. After being off for about six hours (even the circulating fan) it ran for about ten minutes yesterday before shutting down.

Any ideas what's going on?

House fan comes on

Unit is a 1990 model RUUD

Manual thermostat

Capt Worley PE said:

My outside (condenser) unit has stopped working. The contactor was replaced about a month ago (with a unit that looked completely different) and the unit worked for a couple of weeks, then stopped. When the AC guys came, it turned right on.
Well, it quit working again Monday. After being off for about six hours (even the circulating fan) it ran for about ten minutes yesterday before shutting down.

Any ideas what's going on?

House fan comes on

Unit is a 1990 model RUUD

Manual thermostat

Click to expand...

If you manually push the contactor in, will the condenser run?

I haven't got the guts to try that one yet, although it did cross my mind.

The original contactor looked sorta like a mouth harp, but the new one sits on four springs (look like they came out of a pen).

Capt Worley PE said:

I haven't got the guts to try that one yet, although it did cross my mind.
The original contactor looked sorta like a mouth harp, but the new one sits on four springs (look like they came out of a pen).

Click to expand...

Either way, you should be able to tell if the contactor is pulled in, which I'm assuming it's not. For it to work sporadically, it may be a loose low voltage wire. That's what I'm thinking. It could also be a relay, transformer, or thermostat.

But, I would venture it's a loose or broken wire.

Check the low voltage connections on the contactor. Make sure the connections are tight.

Yeah, the contactor isn't pulling in, I'm leaning towards a loose wire myself.

Does this oddity help: The night before it quite working, the compressor and condenser came on about a minute before the circulating fan came on.

Capt Worley PE said:

Yeah, the contactor isn't pulling in, I'm leaning towards a loose wire myself.
Does this oddity help: The night before it quite working, the compressor and condenser came on about a minute before the circulating fan came on.

Click to expand...

If the contactor isn't pulling in, it could be a control wiring issue, as has been mentioned. If the contactor is pulling in and either the condenser or fan or both aren't coming on, it could be a loose power connection. Given that the problem is sporadic, I'm leaning toward a loose power connection.

(Disclaimer: Electrical troubleshooting and repairs should always be performed by a qualified electrician.) :laugh:

The AC guys are coming today, so we'll see what they say. I do think they funked up a wire someplace.

Capt Worley PE said:

The AC guys are coming today, so we'll see what they say. I do think they funked up a wire someplace.

Click to expand...

I think it's the control board.

Fudgey said:

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:Locolaugh:

jmbeck said:

I think it's the control board.

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Might be. I have a feeling they are going to advocate for a new unit.

Capt Worley PE said:

Might be. I have a feeling they are going to advocate for a new unit.

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of course they will

They keep mentioning how old it is, and I keep telling them that the HVAC unit in my parents house is 45 years old.

Maybe you should get one of them new fangled European units. I hear they're better than any of that 'Made in the USA ' crap.

It goes without saying that I'd ask only for superior European product.

Hopefully something with an umlaut in the name.

Capt Worley PE said:

It goes without saying that I'd ask only for superior European product.
Hopefully something with an umlaut in the name.

Click to expand...

These are big in Europe. Incredibly energy efficient.

Capt Worley PE said:

They keep mentioning how old it is, and I keep telling them that the HVAC unit in my parents house is 45 years old.

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Surely not.

Unless there is a problem with the refrigerant circuit, there is no reason to replace.

Unless you simply want a more efficient unit.

Is it a heat pump? If so, I'm going with "faulty Defrost Control Board" FTW.

Fudgey said:

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Well, the thread is called AC question,

well done Fudgey

jmbeck said:

These are big in Europe. Incredibly energy efficient.

Click to expand...

You laugh, but that looks like something Dad and I might rig up to cool off the 'pit' while we are BBQing.

jmbeck said:

Surely not.
Unless there is a problem with the refrigerant circuit, there is no reason to replace.

Unless you simply want a more efficient unit.

Is it a heat pump? If so, I'm going with "faulty Defrost Control Board" FTW.

Click to expand...

Not a heat pump, and for the second time, they came out and the **** thing ran flawlessly. The guy thinks it is either the thermostat or the limit switch on the condensate pump. The thermostat is an ancient unit that looks to be as old as the house, so that may be it. it is getting replaced Monday.

Its so weird the guy said to call him the instant it quit because he wants to see it in non-operative mode and it doesn't seem to want to cooperate with him.

Capt Worley PE said:

The thermostat ... is getting replaced Monday.

Click to expand...

May I suggest a programmable?

Not sure if you have an empty house or not, but the new programmables from Honeywell are pretty nice. For about $100, you can get the visionpro, which will actually "learn" the length of time it takes for your unit to achieve setpoint. Therefore, you can set your occupied times at actual times instead of an hour before in order to achieve desired temperature. When I get home at 5:00, it's always a nice temperature, and I'm glad to know (especially in Alabama) that it's not sitting there running in the butt-heat of the day cooling an empty house.

The recirc mode is nice as well. The fan will operate intermittently whether or not you're calling for cooling/heating.



Now, for $300.....



I didn't even know this was available, and not even sure what all it can do. I just saw it on the Honeywell website. But, it has an HD screen, and pictures of clouds, so that's enough for me to want one. I'm pretty simple to please though.