ac freezing with thermostat off

[alexpio]

Hello, I just realized that my home heat pump compressor keeps running and freezing the line by bypassing the thermostat. I believe the thermostat itself is still in good working order because if I set it to a temperature lower than the outside temperature, compressor and condenser fan come on, and when it reaches the preset temperature, the condenser fan stops spinning while the compressor keeps working and freezing the line. Any idea of what is wrong? Thanks in advance for any help/suggestion.

Alex

[Noon-Air]

Its broken

Call somebody that knows WTF they are doing.

[Stormin Mormon]

I've never seen a thermostat on a freon line. May we have some more information? Line bypassing the thermostat? New one, to me.

It sounds like a controls, relay, and switching problem.

[KJPRO]

Once again, your incompetence is shown. The thermostat the OP is talking about happens to be the one controlling the room temp. Furthermore, a HP has a line thermostat for defrost purposes.

[Gary]

I'm just guessing but it sounds like you're confusing the condenser fan with the inside evaporator fan. It would be very unlikely for the line to freeze if your outside condenser fan wasn't running unless you were running in heat mode & the indoor fan was running. You really need to call a pro before something more serious happens to your system.

[alexpio]

Maybe I didn't explain the problem clearly enough. I meant to say that no matter what the temperature setting of the thermostat inside the house is, the compressor will still run, while the condenser fan will stop once the preset temperature inside the house is reached. Basically the compressor does not respond to the thermostat setting, while the condenser fan does, and as soon as the fan stops spinning, I see ice forming around the line that goes inside the house to the evaporator. This is what I meant by saying "bypassing the thermostat". I agree with you about the nature of the problem, and I was hoping that somebody else had experienced something similar and could be more specific about what to look for.

[KJPRO]

Please excuse the alt.hvac resident idiot... he knows just enough about HVAC to be dangerous to anyone that *will* listen to him. But rest assured, he'll be polite! As you know, that makes up for everything he lacks to be an excellant HVAC tech.

Now getting to your problem... I want to clearify some things that people often get mixed up about. The outside unit "condenser" contains the compressor and condenser fan. The indoor unit "evaporator" is either installed with an air handler or furnace.

So in your case, is it the indoor or outdoor fan that stops running? I would guess that you mean the indoor evaporator motor stops running. While the complete outdoor unit continues to run, including the condenser fan. Either way, this problem should be looked at by someone that has the proper training and tools to repair your unit. While they are there, have them service your unit to insure its running efficiently. As there's no need to waste money on operational cost.

[Stormin Mormon]

That's really strange. On the central AC units I've serviced, the condensor fan and the compressor are on the same relay, so they turn on and off at the same time. If the condensor fan turns off, then the compressor would overheat, in very short ammount of time. I had to replace an outdoor unit one time, for a guy whose condensor fan would run only if he pushed it with a stick.

[new jersey]

Alex Are you in heating mode is this heat pump or as PJ put it line contactor welded

[alexpio]

I'm talking only and exclusively about the OUTSIDE CONDENSING UNIT AND CONDENSER FAN. The squirrel cage blower inside the air handler works fine. Thanks.

[KJPRO]

You're really showing your ignorance the last few days... Compressors don't rely on the condenser fan for cooling purposes! I suppose you never saw a Rheem unit were the compressor is to the side??????

[KJPRO]

EXCUSE ME FOR MAKING SURE!

[Stormin Mormon]

What occurs to me. When the outdoor unit shuts off, the condensor still contains high pressure refrigerant, liquid at the bottom of the condensor. So, it's possible if the condensor fan and compressor shut off, you can still have refrigerant migration, due to the pressure difference.

Makes me wonder if you have a clogged filter dryer, in the outdoor cabinet. Or near the discharge valve. Could be that the filter is acting as a metering device.

If the compressor continues to run, that's a puzzler. How would the compressor continue to get powered, after the contactor opened? Sounds like you have a wiring problem, or a switching and controls problem.

[Gary]

I'd be curious what brand unit you have. Some of the old GE's & Tranes use separate poles on the contactors so its possible for the compressor to run without the fan if the contractor goes bad or sticks like pjm noted.

The freezing up on the line just doesn't make sense unless you're talking about a very short time after the fan shuts off & then it goes away. You could have two problems where the gas is low also. Either way you should have called someone by now. The compressor staying on is a simple problem to fix but you don't want to make it into a bigger one.

[Gary]

I see your point & I don't ever remember running into a scenario like this one but something doesn't sound right. I've seen it plenty of times when the contactor sticks, the blower shuts off & the system will freeze up. I would think that the condenser fan not working would create high enough pressure to keep the suction line over the freezing temperature if fully charged. With the indoor blower not working that would help cool things down but I wouldn't think enough to freeze for any extended period of time because I think the head pressure would start to cancel it out as it builds. That's why I'm wondering if the gas could be low also along with a stuck contactor.

[alexpio]

freezingthe line. Any idea of what is wrong?

OK, I fixed it. I want thank everybody for your help in solving the problem. As .p.jm@see_my_sig_for_address.com suggested, it was a welded contactor. I replaced it, and the ac is running beautifully!

Alex

[Stormin Mormon]

Don't worry, he will send a bill in the morning for consultation.

[new jersey]

[KJPRO]

Yes, as Tony may have learnt something.

[Don Ocean]

freezingthe line. Any idea of what is wrong?

Paul accepts payment in Paypal, Gold or Catfood. ;-p