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big-e 07-15-2010 12:32 PM

Condenser unit quits working on regular basis..
Hello all,

I am currently experiencing a problem with our Heat pump / AC system.

Now that the summer is in full swing, we are running the A/C. The problem we are currently having is that the unit is running just fine (both the condenser and the blower motor etc.). Then al of a sudden, the condenser unit outside stops running. The blower unit inside is still going as normal, but obviously is no longer blowing cold air at that point.

The way we "fix" it is by turning the thermostat to "off", let it sit for a little while (usually only a couple of minutes), turn the unit back to "cool", and everything is working fine again. Till it happens all over again, that is.

The symptoms are very irregular. Sometimes we have no problem again for a week, and other times it happens again the very same day.

I have not been able to find any constant condition when the problem occurs. At first I though it only happened during really hot weather, but now it has happened during cooler spells also.

We do currently have an HVAC technician looking into the problem, but he is assigned through our Home Warranty company, and I question his approach of "replacing stuff and see if that fixes the problem". He already installed a new thermostat, but the problems are still there. Now he is going to replace some circuit board in the condenser unit, hoping that that will fix the problem. In other words, he does not know exactly what the issue is, he is just guessing. I am trying to get the guy to come over while the problem is happening, but he is never able to come on such short notice, so I have no choice to turn the system off and on again, as I don't do very well with heat.

I am still letting the HVAC guy do his thing, since everything is at the expense of the home warranty, but it is still annoying all the same. Already we had a problem where we were out of town for the weekend, the unit broke down and our cats were stuck in a sweltering house for at least a full day. Not cool. (no pun intended)

Does this problem sound familiar to any of you guys, or maybe any other suggestions as to what may cause this behavior?

Oh, our system is a York, with a White-Rogers thermostat.

big-e 07-15-2010 12:47 PM

Update: Well it happened again just now, but with one difference.

The HVAC technician came by this morning, which is when he determined that the condenser unit needs a new circuit board. (He guessed it had something to do with the relay for the defrost function, or something). he indicate that he rewired the unit to bypass this function, since it is obviously not necessary during summer time.

When the condenser unit shut down just now, I started hearing a strong hissing sound (coming from the refrigerant lines). The uninsulated line was extremely hot to the touch, there was very hot air coming out of the unit because of it, and outside, the condenser unit was not running, but making a fairly loud buzzing sound.

It was not doing any of that during any of the previous breakdowns.

needless to say, I turned off the system immediately, as I was afraid of potential damage.

It is probably going to take another week for the new part to come in. Should I have the technician undo whatever he did this morning, since the situation seems more damaging now?

By the way, I turned the system on again, just to see, and again, it is working fine right now :mad:

NitroNate 07-15-2010 01:50 PM

have you checked the plenum and all the duct work for any leaks? other possibilities could be an overcharged system or uncompressables like air in the system. i'm assuming the condenser fan is running the full time the system is on.

hennyh 07-15-2010 02:11 PM

I'd fire the tech. Home warranty companies tend to farm out jobs like this to "bottom of the barrel" techs. who can't make it on their own. The fact that he starts by replacing the thermostat demonstrates his total incompetance. Now he's proposing replacing the control board?? The thermostat and control board tend to be the least problematic parts in the HVAC system.

The system could be overcharged or in need of cleaning. This could cause the high pressure safety switch to shut down the system to protect itself. (so the tech. bypassed this????)

It could also be a marginal capacitor or possible damaged wiring.

Hire a professional tech. and pay out of your own pocket. Don't renew your home warranty.

NitroNate 07-15-2010 02:35 PM

yeah home warranties can be a bit of a joke. they always manage to add a few things they don't cover to make sure you pay some extra out of pocket. i remember one being $50 for evap. coil disposal. yeah, right. that went right into the guy's pocket and he probably tossed it in a dumpster.

unfortunately, for all you good professionals out there, there are just too many bad eggs that you have to sift through first. unfortunately, there is just no really good system for getting the good guys' names out there other than word of mouth from friends and family you trust. sadly, there are too many uninformed homeowners that will recommend companies that do less than stellar work, but they don't know any better.

big-e 07-15-2010 03:15 PM

Thanks for the replies so far, everyone.

As far as the unit itself is concerned..... I just had our regular HVAC guy come over and the unit has been thoroughly cleaned about a month and a half ago. The pressure was also checked at the time, as well as with the new HVAC guy when they first came over to assess the problem, and everything checked out just fine.

I certainly hope he did not bypass the high pressure switch! He did not say anything about that, but who knows what he did ultimately.

As far as the technician himself, apparently he has been in business for over 50 years, so he must be doing something right to stay in business for that long. That being said, working on a home warranty case certainly is not his highest priority, I am sure.

Either way, he just called me about an hour ago (after I complained to him about the latest failure) and he indicated that he is going to install a brand new condenser unit tomorrow morning?!?!?

Not sure how he pulled that one off with the Home Warranty, but I can't argue with that, I guess. And after a $60 service fee, which we already paid on the first visit, there are no other charges that we have to worry about.

We'll see how that plays out tomorrow.

Marty S. 07-15-2010 04:33 PM

Sound to me like a condensor fan motor issue causing the unit to trip on high pressure. When you shut it off then restart that resets the lock out. That doesn't matter now that you're getting a new unit for free, congrats.

beenthere 07-15-2010 05:18 PM

I'm with Marty. Condenser fan motor is stopping. But not the compressor.

And if he bypassed the defrost board. He bypassed the pressure switches. Since they usually run through the defrost board.

Your description of a hissing noise, and the small line being hot, leans towards a condenser fan problem.

big-e 07-15-2010 06:24 PM

Ah, thanks so much for all the input.

As a follow-up on the high pressure....

Are there any other causes for high pressure, other then over-charging and/or dirty coils? Pressure has been checked by different people 3 times in the last year, and a problem was never indicated. Unit is also very clean at the moment.

I just want to make sure we don't have the same problem once we get the new unit installed.

In the mean time, we will make sure to turn the unit off overnight, just in case.

beenthere 07-15-2010 06:59 PM

A bad defrost sensor/thermostat can also cause what your describing. Its easy to test the defrost thermostat. He just needs to use hos ohm meter.

big-e 07-15-2010 07:51 PM

Thanks again for all the replies.

My wife and I bought the house not quite a year ago, and the contract came with a home warranty contract build in (seller paid for it). The house was built in '78, so I am not sure if it is still the original unit, or if it has been replaced at one point.

At this rate we'll have a new system already mostly in place. This HVAC tech already put in a new thermostat and a condenser unit tomorrow. Last winter, we had a new control board installed, as certain parts on it were burnt out which prevented the emergency heating coils to operate properly.

Maybe I just have to bite the bullet and have the rest replaced out of my own pocket.

Marty S. 07-15-2010 08:07 PM

Dirty condensor coils, over charged or fan motor stopped all cause high pressure switches to trip. Coils are clean, freon pressures checked out so all that's left is the fan. Defrost board controls the fan and it's bypassed so process of elimination leaves the fan motor as the trouble maker.

Had one like that when I first started doing service work. Two trips out with the system locked out on high pressure and I couldn't find anything wrong. Third time out replaced the motor even though it tested fine and the problem went away. Intermittent issues suck.

hennyh 07-15-2010 08:51 PM


Originally Posted by big-e (Post 470088)
Maybe I just have to bite the bullet and have the rest replaced out of my own pocket.

I would not mate a new condenser with a decades old air handler/coil/line set.

If you hit the home warranty jackpot and they're actually going to replace the condensing unit then I'd definatley try and get the entire unit upgraded. (A new condensing unit and 1978 air handler/coil isn't wise!!)

My only reservation would be dealing with a home warranty "hack".

Ask the home warranty company for a cash out in lieu of the condenser replacement and pick and choose your own contractor who'll look out for your best interests instead of "whoring out" to these home warranty idiots.

bpr 07-22-2010 11:38 AM

beware of the new condenser new r22 condensers are typically no longer available and would not match up with the indoor coil.go for the new system with 10 year warranty and aprilaire filter at the furnace.its very important that the refrigerant lines be flushed,avacuated, new drier installed.1500 dollar tax credit available till end of year

big-e 07-22-2010 12:01 PM

Thanks for the replies everyone. Upon further investigation (with the help of the technician) we determined that the system has been replaced at some point, so it is not as old as initially thought. Installation of the new condenser was without problems, and the system has been running perfectly fine ever since.

Thank you for all the suggestions. (Still considering replacing the inside unit, though)

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