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Desertboyz · 02-22-2017, 03:38 PM

We have 3 A/C units. Went to start up today and the front will run for a few minutes, then shut down. It doesn't ever seem to start to blow cold air. Other 2 are ok. I checked the circuit breaker, it's ok.

Any ideas?

silverado574 · 02-22-2017, 05:06 PM

Had the same thing happen 2 weeks ago in Georgia. Called Tiffin and explained just what you are experiencing. The tech said the Thermister was bad. It is the little white plastic piece just next to the intake vent on the drivers side. I ordered on for 14 dollars and some change but I unscrewed the one the ceiling and snapped it with my finger and thumb. Put it back and it has been working just fine. Have the new one as a spare if it happens again. There are two wires that you cut and splice and polarity is not an issue.

Desertboyz · 02-22-2017, 06:20 PM

Quote:

Originally Posted by silverado574

Had the same thing happen 2 weeks ago in Georgia. Called Tiffin and explained just what you are experiencing. The tech said the Thermister was bad. It is the little white plastic piece just next to the intake vent on the drivers side. I ordered on for 14 dollars and some change but I unscrewed the one the ceiling and snapped it with my finger and thumb. Put it back and it has been working just fine. Have the new one as a spare if it happens again. There are two wires that you cut and splice and polarity is not an issue.

That was it! I wondered what those little things were. I tapped on it a couple of times and now it's fine! Who would have guessed. I'll order an extra too.
Thanks!

Desertboyz · 03-01-2017, 03:18 PM

Quote:

Originally Posted by silverado574

Had the same thing happen 2 weeks ago in Georgia. Called Tiffin and explained just what you are experiencing. The tech said the Thermister was bad. It is the little white plastic piece just next to the intake vent on the drivers side. I ordered on for 14 dollars and some change but I unscrewed the one the ceiling and snapped it with my finger and thumb. Put it back and it has been working just fine. Have the new one as a spare if it happens again. There are two wires that you cut and splice and polarity is not an issue.

The problem is back. The Thermister must be bad. Do you have a part number? Where did you order from? Thanks

garykk · 03-01-2017, 04:45 PM

Call Tiffin parts, it a AC ceiling sensor part number 5019418. Or you can go to the Tiffin site, owners, parts

luvlabs · 03-02-2017, 08:06 AM

Thermistors have a very low failure rate. What you describe in your original post, short cycle, no cooling, sounds more like a set of bad capacitors. I would replace both the start and run capacitors. If that doesn't work, something else is going on with your A/C unit.

billdreamlv · 03-02-2017, 08:41 AM

Quote:

Originally Posted by luvlabs

Thermistors have a very low failure rate. What you describe in your original post, short cycle, no cooling, sounds more like a set of bad capacitors. I would replace both the start and run capacitors. If that doesn't work, something else is going on with your A/C unit.

I agree with Roger. You have to hit a thermistor with a hammer in order to break it. The MTBF on a thermistor is millions of hours. But it does sound like it could be a cap or the connections to the thermistor are loose. Try to tighten up the connections on the back of the Thermostat. Be careful with the cap. It can bite you. Shut the power off and then ground both sides with an insulated screwdriver before you touch it.

Desertboyz · 07-25-2017, 10:10 AM

I'm following up on my old post. Everyone that concluded the problem was more than a thermister was correct!

The motor mounting brackets broke and caused the fan to lose several blades. The motor and fan were replaced.

And then the same thing happened to the middle unit. And then the same thing happened to the back!

After researching, this is a known issue for Coleman Mach 8 A/C units manufactured in a certain time period. Air Excel tried to say they weren't "aware" of the problem. I finally got a hold of a tech who cared. He sent replacement parts. We had them installed. We have A/C again! Fortunately we are in the Upper MI Peninsula and the heat hasn't been too bad.

jagbuxx · 07-25-2017, 10:33 AM

Hmmm, my coach in the shop now for this same/similar issue.
Front a/c unit on low fan cycles 27 seconds on, 47 seconds off.
On high fan, the fan stays on but the compressor still goes 27 seconds on, 47 seconds off.
Curious as to what they'll find.