Replacing TT AC

Yes, ordered one online and installed it with no problem. Ordered the same as what was there. Did this for a friend to help them out. A/C was much cheaper online that thru a dealer.

OP here with an update. With the help of responses here, I was able to reconnect the burned connection and the AC is now back in action!

No thanks to the two RV places who were involved, or to Dometic. Those three entities could have at least steered me in the right direction instead of telling me there was no alternative to a new $500-800 rooftop unit.

Cost me $2 in parts from Home Depot!! Plus a bunch of time, of course, but that's what being retired is all about.

Thanks to everyone for your input.

DFord wrote:

sayoung wrote:

If the OP uses a meter on those terminals , Have on safety goggles as it's not BS that using a meter on compressor terminals sometimes blows out the terminal.. I know from experience. It's rare but can happen and oil & refrigerant in the face isn't fun.
Original post led me to believe some AC hack had already tested & told him unit needed replacing because the capacitor "cannot " be replaced per tester. Only now shows compressor with appearance of bad terminals. While getting klaxon get a terminal repair wireing kit that has the leads with pre-crimped terminals. Without the crimping tool you'll have bad connections most of the time.

The compressor terminals come through a molded glass block so they won't leak. I have seen overheating cause them to blow out the terminals resulting in the loss of all the gas. When that happens, there's no choice but to replace the compressor or the whole unit. Because there's no sign of any leakage in this case, the integrity of the glass seems to be sound. I can't image why applying the probes of an ohm meter to the terminals would cause any problems.

I always pried the wire connectors off the compressor carefully with a screwdriver using another tool as a fulcrum. (as oppose to grabbing them with pliers to pull them off) That must be done before any ohm readings are measured. The first test should be between the terminals and the copper tube coming out of the compressor. If there is any sign of continuity (even at the highest range on the meter), the compressor is toast. The reading between COMMON and RUN should be lowest. The reading between COMMON and START should be a lot higher and the reading between START and RUN should be the highest. The exact numbers they should show are hard to find without access to the complete documentation for the compressor.

Duh, I've been working on HVACR equipment since I was 16, retired 4 yrs ago after working on everything from small wine cooler to 200ton chillers. Blowing the terminal can & will happen , maybe 4 times in my career . Don't lose an eye.
Also when testing continuity to ground you need a meter that can read megohms or a true megger . If not you will mis-diagnose a lot of grounded compressors. But usually tripping breaker at that point

Riley, I've never had any problem with RUN capacitors hold a charge - START capacitors are another story but most have a resistor across their terminals. The HF multimeter should be good enough to make your tests. While you're there, take a look at the RUN capacitor. It may be okay. It looks like your problem was due to a bad crimp on the wire from the Klixon but if there's any sign of deformity on the RUN capacitor metal can like a bulging top, it's no good - don't try to reuse it. It should look new, like it just came out of the box.

All you might need in the way of clean-up tools would be a small wire brush to shine up the terminals.

I mentioned prying off the old connectors with a screwdriver instead of grabbing them with pliers. You'll need something to pry against under the screwdriver and then slip the tip under the edge of the connector and slide it up and off. That way, they shouldn't be damaged. They should fit tight when you put the RED and WHITE wires back on the compressor as should the new connector on the new Klixon.

Again, thanks to all for the information and advice. BTW, before this problem happened the AC cover had never been removed (in case anyone is wondering if a prior repair or something caused this).

I'm heading over to the RV now to clean up the terminals and better assess what it looks like. I'll take pictures.

I've printed the instructions for testing for continuity and will look at the wikihow links Don sent before testing. I only have the very cheapest multimeter (the one you get for free at Harbor Freight). I'll go get a better one before I test.

So, to summarize:

1. test for continuity
2. if that's good, purchase the correct klixon and run capacitor
3. wire them in, insulate as needed and and secure them somehow (zip ties?)

Did I get the above steps correct?

Also, is there any chance the capacitor is holding any charge? the RV hasn't been connected to AC power in 4 months.

Don, I'll PM you my contact info, we can definitely have some BBQ when you're in Dunedin!

DFord wrote:

sayoung wrote:

If the OP uses a meter on those terminals , Have on safety goggles as it's not BS that using a meter on compressor terminals sometimes blows out the terminal.. I know from experience. It's rare but can happen and oil & refrigerant in the face isn't fun.
Original post led me to believe some AC hack had already tested & told him unit needed replacing because the capacitor "cannot " be replaced per tester. Only now shows compressor with appearance of bad terminals. While getting klaxon get a terminal repair wireing kit that has the leads with pre-crimped terminals. Without the crimping tool you'll have bad connections most of the time.

The compressor terminals come through a molded glass block so they won't leak. I have seen overheating cause them to blow out the terminals resulting in the loss of all the gas. When that happens, there's no choice but to replace the compressor or the whole unit. Because there's no sign of any leakage in this case, the integrity of the glass seems to be sound. I can't image why applying the probes of an ohm meter to the terminals would cause any problems.

I always pried the wire connectors off the compressor carefully with a screwdriver using another tool as a fulcrum. (as oppose to grabbing them with pliers to pull them off) That must be done before any ohm readings are measured. The first test should be between the terminals and the copper tube coming out of the compressor. If there is any sign of continuity (even at the highest range on the meter), the compressor is toast. The reading between COMMON and RUN should be lowest. The reading between COMMON and START should be a lot higher and the reading between START and RUN should be the highest. The exact numbers they should show are hard to find without access to the complete documentation for the compressor.

Thanks for wading thru the BS from some posters. I only have 40 years of working on RV roof AC's. But, I have NEVER seen the compressor 3 spades BLOW OUT. I also have NEVER seen a Compressor case or any part or the compressor Blow Out oil and Freon. I also would replace the Klixon and then test the AC. CHEAP to do that. BTW, that is not a capacitor in the real sense that failed. So, the OP was getting very bad advice from so called Techs. Doug

sayoung wrote:

If the OP uses a meter on those terminals , Have on safety goggles as it's not BS that using a meter on compressor terminals sometimes blows out the terminal.. I know from experience. It's rare but can happen and oil & refrigerant in the face isn't fun.
Original post led me to believe some AC hack had already tested & told him unit needed replacing because the capacitor "cannot " be replaced per tester. Only now shows compressor with appearance of bad terminals. While getting klaxon get a terminal repair wireing kit that has the leads with pre-crimped terminals. Without the crimping tool you'll have bad connections most of the time.

The compressor terminals come through a molded glass block so they won't leak. I have seen overheating cause them to blow out the terminals resulting in the loss of all the gas. When that happens, there's no choice but to replace the compressor or the whole unit. Because there's no sign of any leakage in this case, the integrity of the glass seems to be sound. I can't image why applying the probes of an ohm meter to the terminals would cause any problems.

I always pried the wire connectors off the compressor carefully with a screwdriver using another tool as a fulcrum. (as oppose to grabbing them with pliers to pull them off) That must be done before any ohm readings are measured. The first test should be between the terminals and the copper tube coming out of the compressor. If there is any sign of continuity (even at the highest range on the meter), the compressor is toast. The reading between COMMON and RUN should be lowest. The reading between COMMON and START should be a lot higher and the reading between START and RUN should be the highest. The exact numbers they should show are hard to find without access to the complete documentation for the compressor.

You got a lot of useful information here.

My 13 month old Dometic gave out and had to be replaced. I talked to Dometic and they extended the warranty BUT I had to have it repaired at a approved shop. Well I tried finding one and after a long search the two local places one was a 6 month wait and the others reviews were absolutely horrible.

I bought a replacement on eBay and my brother friend and I replaced it ourselves. The hardest part is getting the units on and off the roof.

I hope the repairs suggested work out for you!

Safe and happy travels!

Dave

DFord wrote:
I can't imagine why no one has told you the truth here. That's the compressor in the picture and those are the wiring terminals! The wires are stuck on the terminals with spade connectors. I'd try to pull them off and then "ohm out" the compressor to see if it's shorted or open. If it ohms out correctly, I'd clean up the terminals and re-attach the wires.

The wire from the "Klixon" (overload) to the "Common" terminal on your compressor is burned up. The terminals are called "Common" - "Start" - "Run". Clockwise from the terminal that's burnt.

If the compressor ohms out okay, I'd try replacing the Klixon and the capacitors to see if the compressor will run before scraping out the whole thing.

https://www.wikihow.com/images/thumb/6/6a/Check-an-AC-Compressor-Step-10.jpg/aid9606691-v4-728px-Check-an-AC-Compressor-Step-10.jpg (After viewing this image, use the "back button" on your browser to return to this message.}

I borrowed this image and text from this link: https://www.wikihow.com/Check-an-AC-Compressor
Purchase a multimeter and set it to continuity. There should be a dial on the front of your multimeter. Set this dial to continuity so that you can test each individual terminal to determine where the fault is. Continuity tests whether there is an electrical flow between the terminals. If there is no flow, it’s likely that the terminal is broken or damaged.

If you can get the numbers off the Klixon, you can get a replacement online. Local suppliers are usually reluctant to sell to the customer.

The Klixon is attached to the COMMON Terminal.
The White wire is on the RUN terminal.
The Red wire is on the START terminal.

If the OP uses a meter on those terminals , Have on safety goggles as it's not BS that using a meter on compressor terminals sometimes blows out the terminal.. I know from experience. It's rare but can happen and oil & refrigerant in the face isn't fun.
Original post led me to believe some AC hack had already tested & told him unit needed replacing because the capacitor "cannot " be replaced per tester. Only now shows compressor with appearance of bad terminals. While getting klaxon get a terminal repair wireing kit that has the leads with pre-crimped terminals. Without the crimping tool you'll have bad connections most of the time.

I threw our 2 year old Dometic as off the roof and replaced it with a Atwood for a few reasons. First the Dometic would just not run reliably on a 4k generator and thats with all the gizmos added on and the local Yamaha factory dealer going through the generator and saying there is nothing wrong with it. The AC also on occasion would trip my house breaker when plugged in. Also it was incredibly noisy when running and the amout of cold air it did put out never really reached very far in the trailer.

The Atwood is magnitudes quieter, runs off of 2k watts if needed and throws a stiff ice cold breeze 15-20'. It was basic to install, 4 clamp screws and three wires. Worth every penny.