Trane Heat Pump

I have a Trane Heat Pump that froze solid with ice last winter when we had all the snow here in the northeast. Since I’m on a very tight budget, I spent a lot of hours trying to diagnose the problem myself. Everything pointed to the defrost control board, however, I did all these test on it then and everything checked out to the circuit boards specs. Anyhow, I had an HVAC guy at a local Lowes store told me how to force a defrost on it and from then on it was fine until yesterday. Same thing all over again. Except this time the fan on top is vibrating quite a bit. I had some guy come over that was referred me by a former co-worker tonight and paid him $75 to look at it and he said the whole unit had to be replaced. For some reason, I was thinking a bad compressor would just stop working all together. Any ideas, greatly appreciated…


Steve :frowning:

The defrost board shoud have some jumpers to program the defrost interval. If it is set for 45 minutes, change it to 30 min.

When it is really cold these units will vibrate and rattle.

Sounds like you had an “installer” look at it rather than a technician.
Did he even put pressure gauges on it?

Thanks, I wasn’t really watching him that close and it was 8 o’clock at night. He did have some gauges hooked up and said something went all the way around after a couple of minutes. Not sure what that was.



I forgot to ask the age…

These are the original 2 ton Trane units that came with the house when it was built in 99’.

I would say it is worth fixing, may just need a proper charge and a new capacitor.

A new R410 type will be cheaper to operate but the initial cost will be high.

Thanks Bruce. I agree and I think I’ll treat this like a cancer diagnosis, due to the potential expense. That is, I’ll get a second opinion from a well known reputable HVAC company here on Monday.


You could have had a real HVAC guy there for that.

Defrost is not an easy thing to deal with.

unplug defrost sensor.
install ohm meter across sensor leads.
disconnect outdoor fan wires from def board
run unit in heat till the defrost sensor closes
note the pressure. convert it to temp.
Jump the sensor terminals on the def board.
accelerate the def board clock till it initiates defrost.
check for the def sensor to “open”. note the pressure/temp.
shut everything off and hook back up.

if anything doesn’t work, change the part.
refrig pressures should be correct in each phase of operation
reversing valve check
give me the temp/press of the def sensor for evaluation.

need mdl#

unbalanced fan = ice damage to the fan blade.

Trane compressors don’t go bad because of iceing.



You are correct about the $75. The guy that referred him has about 35 rental properties in the area and he said he’s used him for years, so he must have some trust in him. Anyhow, lesson learned, I should have just gone to the HVAC company I had been using in the past and they’ve been around for 40 years. I’ll come back here and let everyone know the verdict when I find out on Monday.



Update on the Trane Heat Pump:

Well, last winter when I posted issues I was having with this Heat Pump freezing up and now again this winter, I have finally gotten things resolved. I learned my lesson w.r.t. using a freind of a freind to look at my system to save a few dollars. Anyhow, that clown had to be the biggest con-artist ever and I’m glad I had sense enough to see through him.

Long story short, I went back to the company I had used for years and had them come out. I paid them $95 to tell me that for starters I would need a new fan, fan motor and replace the capacitor. They wanted $446 for the parts and 2 hours labor to install. I found the parts on-line for $309 and put them on myself. I did pay the same tech to come back out and check everything out once more to see if there was anything else going on. Everything is running great now and the tech didn’t have to do anything else.

What bothers me was that the one thing that was missing that caused all of my problems in the first place (both this Winter and last) was the fan motor wasn’t plugged into the defrost control board the whole time. The fan motor was replaced by some HVAC hacker that a Home Warranty company sent out here in 2006 right after I bought the house. They hooked the fan up straight into the contactor and did not connect to the DFC board at all. I wouldn’t have picked up on this if I hadn’t opened up my identical downstairs unit to compare when I was wiring up the new fan. Anyhow, I have $574 in the total repair, doing the work myself with the technical expertise of a company I had previously used.


Steve :slight_smile:

Glad you got it sorted out. I like to keep spare parts on hand since I have two identical units. Online prices are not too bad so its a good idea to keep the parts that are most likely to fail. Contactor, outside fan, capacitor(s), t-stat and defrost board for heat pumps. I have never had an HVAC tech come to any house I have owned for repairs… so far. The guy that installed my new heat pumps wired the variable speed blowers wrong. It pays to learn these things and do your own troubleshooting. We had company once and the A/C unit for their end of the house quit during the heat of summer. They were very surprised when I had it running an hour later after finding the problem and replacing the compressor cap with one I had sitting on the shelf. The unit was only about 5 years old when the cap went out.