Any heat pump or a/c guys out there?

mdaudioguy

Before I can even track down the cause of my last electrical problem, I've been hit with another...

We have a Carrier heat pump system, probably about 5 years old now, maybe 6. Last night the house was fairly warm, and with my allergies, having the windows open this time of year doesn't work well. Turned on the a/c to bring the temp down a little - or at least I thought I did. Seems the outside unit isn't kicking in. I'm probably going to call an expert, but thought I'd look for something obvious first.

Pulled the cover off the back and found a control board. I noticed it has a couple little LEDs on it for Comm Status - green and amber. The amber one is lit. Hmm. Pulled a manual online and found that this thing will flash a troubleshooting code, so I lowered the thermostat to send the signal telling the unit to start cooling, and it flashed a code that the manual said means:

Fault: Thermal Cutout
Possible Cause and Action: Compressor voltage sensed after start---up, then absent for 10 consecutive seconds while cooling demand exists. Possible causes are internal compressor overload trip or loss of high voltage to compressor without loss of control voltage.

So I tried shutting everything off at the breaker box - high and low voltage all at once. After a few minutes I brought it all back up. This time I got a different code:

Fault: No 230V at Compressor
Possible Cause and Action: Compressor voltage not sensed when compressor should be starting. Disconnect may be open or contactor may be stuck open or there is a wiring error.

Is it just not my week? At this point, I just want to make sure the service guy doesn't rip me off... what's it sound like?

Should I try anything further on my own? Yes, I'll make sure the power supply is off, and yes, I'll discharge the capacitor first.

gdb

It might be the centrifugal fly weights/contact points aren't throwing enough juice on start-up....if your motor even utilizes such a set-up. Definitely request the senior tech be sent for the service call, there's a lot of yahoos doing that work that shouldn't!:eek: Angie's List perhaps?Good luck!

treitz3

Where the VAC comes into the outside unit, check the voltages with the power on at the bottom of the switch and then check them at the top of the switch. Powered up, you should have close to 120/120 using the incoming ground. There is an arm that has a spring to open the contact. Make sure that contact is clean and that the arm moves freely [do this with the power off].

Then you can check the capacitor. There will most likely be 3-5 wires connected to it. Make sure you note where the wires go as you don't want the cap installed backwards. The fact that the fan doesn't run when you turn it on leads me to believe that it's the switch [or relay] not giving the outside unit any voltage to begin with.

mrbigbluelight

^^^^ Good advice.

Mdaudio, do you have a Model # on that Carrier unit ? That can help a lot.

Also, is the contactor TRYING to pull in ?
If, as Treitz mentioned, you have power coming in on all legs TO the contactor, but nothing OUT, then the question is, is the contactor TRYING to pull in ?

You can usually hear if it is; buzzing, etc.
There'll be 2 leads for the contactor closing coil.
If you have a voltmeter, measure across these leads.

ASSUMING you have a 220v contactor coil:
(a 220v coil will have one side 110v hot all the time, the other side gets the other leg of 110v when the compressor is called to be on)

If you have ZERO voltage ACROSS the coil, then measure each side to ground.
If you have 110v on one side to ground, and 110v on the other side to ground, that means you have an OPEN overload of some sort.
(the 110v to ground on each side with 0v across means you're measuring the same phase/leg on both sides).
This probably means:
An open high-pressure cutout (which is probably reset manually)
An open internal thermal overload on the compressor (which resets itself).

The original fault code did mention: "Possible causes are internal compressor overload trip ".
That internal compressor overload trip is a thermal trip. It'll reset itself, but is an indication of high head pressures. Usually caused by the condensor (outside) coils being dirty/clogged.

Mike Reeter

Our neighbor just had a five-six year old Carrier Heat Pump replaced this past week,said it was still under warranty,he paid a little extra to upgrade to a more efficient model.

By chance yours still covered under warranty?

Polkie2009

I'm going out on a limb and say your contacts or the terminals connecting to the contacts are fried.

mdaudioguy

mrbigbluelight wrote: »

Mdaudio, do you have a Model # on that Carrier unit ? That can help a lot.

It's a 25HPA - manual here: http://www.xpedio.carrier.com/idc/groups/public/documents/techlit/25hpa-2si.pdf

I appreciate the advice of all! Thanks!

mdaudioguy

mrbigbluelight wrote: »

If, as Treitz mentioned, you have power coming in on all legs TO the contactor, but nothing OUT, then the question is, is the contactor TRYING to pull in ?

You can usually hear if it is; buzzing, etc.

I don't hear any noise at all from the outside unit.
EDIT: There is a single loud click about 10 or 15 seconds after a cooling signal is sent.

The original fault code did mention: "Possible causes are internal compressor overload trip ".
That internal compressor overload trip is a thermal trip. It'll reset itself, but is an indication of high head pressures. Usually caused by the condensor (outside) coils being dirty/clogged.

Everything looks clean and clear. I've given it plenty of opportunities to reset... cycled the power and everything.

disneyjoe7

mdaudioguy wrote: »

Before I can even track down the cause of my last electrical problem, I've been hit with another...

What is the problem? I wonder if you could have a loose neutral or something going on.

obieone

Here's what you need to do: Call an hvac company.
NOT Sears or ARS. Look for a company with the Carrier logo in their ad in the Yellow pages. When you place the call, give the dispatcher the Model and Serial number of the condensor, and the symptons you're getting. This will wil help them determine who best to send.

Sorry, but there's too many variables, and trying to t-shoot it over the net will take forever. Especially with a high end system like yours.

Good luck.

mdaudioguy

obieone wrote: »

Here's what you need to do: Call an hvac company.
NOT Sears or ARS. Look for a company with the Carrier logo in their ad in the Yellow pages. When you place the call, give the dispatcher the Model and Serial number of the condensor, and the symptons you're getting. This will wil help them determine who best to send.

Sorry, but there's too many variables, and trying to t-shoot it over the net will take forever. Especially with a high end system like yours.

Good luck.

Oh I plan to, since it's not something obvious. The company I bought it from is owned by a guy I know - got a great deal on it when I bought it, but a couple of years ago, their tech came out and all he did was replace 2 fuses, and then proceeded to chat for 45 minutes and billed me for an hour... I mean, it was probably his minimum, but still...
Anyhow, just wanted to avoid paying for something, if someone on here, by chance, knew precisely what it was.
This is high end?

Hawkeye

Ed, several years ago I had the same problem twice in two years. Seems it was the start capacitor on the outside unit. After watching and paying for the "tech"( I use the term loosely), it was swollen and misshapen. The next time it happened, I bought the cap for next to nothing and replaced it myself.

Now that I live in MD and have oil heat and regular AC, I'm forced to pay the "tech":mad: I'll just watch the next few times he's here!!

Gordon

Polkersince85

If you have power coming to the unit, it could be the relay. Call a pro, Just for future advice, always cycle the unit at least once a month during the off season. Keeps things lubed, the caps charged and bearings free. Plus if you have a problem you know it before you need the cooling.

mdaudioguy

Hawkeye wrote: »

Ed, several years ago I had the same problem twice in two years. Seems it was the start capacitor on the outside unit. After watching and paying for the "tech"( I use the term loosely), it was swollen and misshapen. The next time it happened, I bought the cap for next to nothing and replaced it myself.

Now that I live in MD and have oil heat and regular AC, I'm forced to pay the "tech":mad: I'll just watch the next few times he's here!!

Gordon

Yes! Nice move. I know there are some real good techs out there, and others who just follow procedures and replace parts without some good diagnosis...
Trust me, first thing I did was eyeball that capacitor real good, hoping to see it bulging.

mdaudioguy

Polkersince85 wrote: »

If you have power coming to the unit, it could be the relay. Call a pro, Just for future advice, always cycle the unit at least once a month during the off season. Keeps things lubed, the caps charged and bearings free. Plus if you have a problem you know it before you need the cooling.

Actually, it's a heat pump, too, so it gets a workout year-round in MD. A couple weeks back, it wasn't too cold, but cold enough for the heat to kick on, and I remember noticing it was running on auxiliary heat mode - so it's probably been down for several weeks, possibly a month. At least it didn't happen in mid-winter... Could have cost me a fortune BEFORE I noticed!

treitz3

mdaudioguy wrote: »

There is a single loud click about 10 or 15 seconds after a cooling signal is sent.

Did you measure the incoming voltage and the voltage that leaves the switch [or relay]? Using the incoming ground, you should have 120/120 VAC on both legs at the top and the bottom [or side to side, depending on how it's mounted].

mdaudioguy

treitz3 wrote: »

Did you measure the incoming voltage and the voltage that leaves the switch [or relay]? Using the incoming ground, you should have 120/120 VAC on both legs at the top and the bottom [or side to side, depending on how it's mounted].

Finally got around to this today. Of course, I couldn't find my multi-meter, so had to borrow my brother-in-law's...

Incoming voltage? About 0. Yeah, 250V before the fuses and 0 after. $12 for a pair of 30A fuses at Lowe's. Yippee! :biggrin: