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Trane heat pump with a bad sump heater

I have a Trane XL1400 3 ton heatpump. The breaker for the outdoor unit instantly trips and this is with the air conditioning thermostat set to off, so my problem lies on the line side of the contactor, L1 and L2. I have the wiring schematics for my unit and I discovered that if I detach the wire going from either L1 or L2 to the sump heater that the breaker will no longer trip. What I need to know is if the sump heater is something that is separate from the compressor and can be replaced without disturbing the it. I'm fairly knowledgeable about electronics and electrical wiring but know absolutely nothing about the freon side of an air conditioner. Thanks.

Reply to
Jerry
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The sump heater can be replaced. If it is a scroll compressor, it is a band type around the outside of the compressor near the bottom of it. If it is a recip, it is in a well on the underside of the compressor. Failures of the sump heaters are not that uncommon, and are usually a fairly simple repair, though the ones on the recips can be a bitch to get to. It would be a good idea to replace the thermostat that controls the sump heater at the same time. Larry

Reply to
Lp1331 1p1331

I think what you're referring to is the crankcase heater. The heater is on whenever there is power on the condensing unit. There are two types you will see on HVAC compressors. One looks like a long screw type hose clamp that wraps around the lower part of the compressor and the other is a ceramic cartridge that slips into a well in the side of the lower crankcase of the compressor. The ceramic heater will be coated with a heat transfer compound that resembles white grease and held in place with an internal spring clip. If either type heater is shorted somehow, it will trip the circuit breaker. The heaters are easily replaced without disturbing the hermetic system. There are some heater systems that apply a limited current to the motor windings to keep the compressor warm but I haven't seen it on a home HVAC system.

TDD

Reply to
The Daring Dufas

Larry, thanks for the info. Can you tell me how in the world I can get access to the compressor and sump heater. This Trane XL1400 looks like a large box, seems to be surrounded on slightly over 3 sides with the aluminum coils. 2 side panels come off, one revealing all the electrical connections and controls along with the transfer valve. The opposite side comes off also but behind it was just more cooling fins. It almost looks like you have to go in through the top but for the life of me I can't figure out how to take the large cover off the top of the unit. Thanks again.

Reply to
Jerry

Take the compressor out. The heater will come with it :-)

Look for the 5/16th screws around the perimeter.

Then you'll see that you need a small well-trained monkey to get at the heater from there :-(

Reply to
.p.jm.

Paul, thanks, I will look for the screws. I suspect that I might be able to get to the heater after taking the fan off the top. Looks like I might need some sky hooks to suspend myself upside-down while I try and reach the bottom of the compressor. I hope the smiley face that went with the "Take the compressor out" meant what I think it means. Thanks again.

Reply to
Jerry

Thus the need for a monkey. A very small one. That's handy with tools.

One place I worked, we used to keep a really really small guy on staff for such things. We would hang him by his feet and lower him into the unit. Then one day he slipped, and we couldn't get him out. So we put the cover back on and left.

Depends how much you like taking compressors out :-)

Reply to
.p.jm.

Considering I know absolutely nothing about the compressor side of an airconditioner I think I'll try it the hard way first. What I'm wondering is if the unit would work without the sump heater. Reading a article from Trane, they state this about the sump heater:

"This device is designed to warm the compressor crankcase or sump, in order to prevent or deter refrigerant migration during the compressor off cycle. Compressor crankcase heaters are required for low ambient cooling operation."

I live in Tampa Florida and right now the ambient temp is anything but low. Barely makes it into the upper 70's by morning with highs around 90+. Might it work without the sump heater?

Reply to
Jerry

Jerry, the unit will work fine for now with the heater disconnected. I'd replace it before winter though. On most of the XL Tranes, there are four clips that hold the top cover on. You push the cover down slightly and pull the bottom edge out slightly at the ame time. If you have someone to help you, it makes it a lot easier. Otherwise, you will get one side loose and then when you try to do the other side, the first side locks back into place. Larry

Reply to
Lp1331 1p1331

Thanks Larry, I may just try and take a look at the compressor with the top off and see what I'm in for with replacing the sump heater. It's a bitch working outside on that unit when It's 90 and the sun is beating down on you. A job that would be easier if left for November.

Reply to
Jerry

There are some heater systems that apply a limited

This is common practice by the manufacturers in resi systems.

Reply to
Steve

Educate me, what brands? I'd like to know so I don't break one. Some years ago, a friend asked me to check out a system he had just installed because he thought something was wrong with it. I thought something was wrong too until I read the documentation and spoke with the distributer. I had no experience with the electronically controlled blower motors at the time and had to be educated. I started repairing AC units back in the early 1970's and have seen a lot of changes since then. The modern equipment is like a new toy for me when I discover how they work.

TDD

Reply to
The Daring Dufas

Rheem/RUUD, most Carrier/Bryant/Payne, as well as most ICP products. when you open one up that still has the *ORIGINAL* contactor, you will probaly find that it has a single pole contactor with a shunt. FWIW, *MOST* scroll compressors use the start windings for CCH.

Reply to
Steve

Thanks, I hadn't really noticed it on the wiring diagrams. In truth, I haven't had to replace that many scroll compressors. Tomorrow I have to help a friend, who I do a lot of HVAC work with, change out a 1.5 ton recip. I will look for the circuit now and be careful to make sure the crankcase heat is on for any of the scroll compressors I come across. And I thought the manufacturers were just being cheap with that single contact.

TDD

Reply to
The Daring Dufas

I do remember one time Turtle asked me, and I explained it to him. He already knew, he was curious if I knew.

Reply to
Stormin Mormon

First off I would like to thank Larry, Paul, Steve, The Daring Dufas and That One for taking the time to help me with my problem. I decided for now to take Larry's advice and just turn the unit on because with the hot weather the heater wouldn't be needed. I did and it works just fine, I guess I'll put off the repair until the fall when it's a little cooler down here in Tampa. I did discover that I had the parts list for the unit all the time, it came with the units documentation and the sump heater (part # HTR1298) is the cigar shaped type. The settings of the thermostat that controls the heater (part # THT0811) has settings that I would not have expected, closed at 73 and open at 105. I would have thought they would have been much lower but they are what they are and I'll probably replace it also. If removing the original sump heater proves to be more than I can handle I may consider one of the aftermarket wrap around type heaters, it may be easier to install. Thanks again

Reply to
Jerry

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