AC Thermostat Bypass - Short Cycle |
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fwunder
Senior Member Joined: 04 Oct 2013 Location: New Jersey Online Status: Offline Posts: 1676 |
Topic: AC Thermostat Bypass - Short Cycle Posted: 16 Jul 2021 at 7:26pm |
For those that might be wondering why I'm making such a big deal about AC. It's not for me and it's not for DW. We can deal with it. We got some trips coming up where we will have to leave Theo, the camping cat, in the rpod while we attend some functions. Don't want to cook her or worse, get her mad at me while we're gone ( self preservation )!!
I did order a WiFi (internet) temp remote so I could get an alert if pod starts cooking. f
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2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 17 Jul 2021 at 6:24am |
Good idea to take a look at the EVAP coil just to eliminate it's freezing up as a possibility, but I doubt it if it's hot in the trailer.
If the voltage is good but the compressor is cutting out and it's not the stat or the Easystart then it's possible it's the compressor thermal overload switch, especially since its happening more when it's really hot. Do a search for the Dometic manual, there is a schematic toward the end that shows where the switch is connected. You should be able to test it with a voltmeter with someone inside turning on the a/c. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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fwunder
Senior Member Joined: 04 Oct 2013 Location: New Jersey Online Status: Offline Posts: 1676 |
Posted: 17 Jul 2021 at 7:37am |
Good tip OG. I located it on diagram. I wonder how long the switch would remain open since it seems to short cycle over just a few minutes.
Of course, it's working fine this AM. I'm going to just let it go all day. Supposed to be another hot one. I finally figured out that I can see evaporator coils from below with air distribution cover off. Also checked that thermistor is where it supposed to be. |
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2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 17 Jul 2021 at 8:54am |
Probably the switch will close again pretty quickly as it cools, it's just a little poppet sensor. If it's open when you get the short cycle then either it's bad or it's doing its job and your compressor is overheating. If it's bad then it's a cheap fix but if the compressor is overheating and the condenser coils are clean then you have $$$ issues.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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fwunder
Senior Member Joined: 04 Oct 2013 Location: New Jersey Online Status: Offline Posts: 1676 |
Posted: 17 Jul 2021 at 1:09pm |
Micro-Air still thinks it is a line voltage problem somewhere. Just happens to be heat related.
No more testing today cuz big storms rolling through. Gave us a nice 20 degree temp drop! Until then, AC was work fine all day. The EasyStart is supposed to catch compressor overload - D21 led on. Very frustrating problem. |
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2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
|
fwunder
Senior Member Joined: 04 Oct 2013 Location: New Jersey Online Status: Offline Posts: 1676 |
Posted: 17 Jul 2021 at 4:09pm |
Electrical Demons!!
So storms passed, sun came out and started warming up again. About 4:00 PM I noticed on remote the interior humidity and temp rising. Humidity rising fast. Ruh Rho! Damn. Yep, it was short cycling. OK, so this time, just for grins I pulled out the 25 foot shore power cord I keep in the locker. I have a home set and a camping set so I don't have to keep packing and unpacking (poor man's pedestal). Anyway, I hook it up and plug into different garage circuit. You guessed it! When I tuned on AC, it got cold fast and has been working as expected for last hour. Wow, if that has been the problem it's really a big time gotcha! If it keeps working, I really want to figure out if it is cord, cord end(s), wall plug, etc. BTW, this little Govee WiFi temp/hygrometer is really handy. I see the inside temp is now 72.1 and humidity is 49 and dropping. f
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2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
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fwunder
Senior Member Joined: 04 Oct 2013 Location: New Jersey Online Status: Offline Posts: 1676 |
Posted: 17 Jul 2021 at 4:10pm |
Ya know, I just thought...maybe it's the rPod shore power inlet? Could be changed cords wiggled something. Hmmm. Lot's to check out.
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2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 18 Jul 2021 at 10:48am |
I thought you'd already checked the line voltage earlier? Where did you check it and was the a/c on when you did it? There can be a significant resistive drop between the home panel and the a/c so you need to measure at the a/c itself while it's running.
I don't know of anything other than low line voltage to the a/c compressor that would cause it to overheat that a bad cord or connector could cause without also tripping a breaker. I've overheated a connectorsll before running the a/c from a 15A circuit without tripping a breaker. The a/c takes so close to the breaker trip point that it's kinda a race between what will overheat first. That's why it's so much better to put in a 30A dedicated circuit for the trailer. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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fwunder
Senior Member Joined: 04 Oct 2013 Location: New Jersey Online Status: Offline Posts: 1676 |
Posted: 18 Jul 2021 at 11:55am |
I did check line voltage earlier and it checked fine at the time - 118v @ RV plug onto garage. The only thing I changed was shore power cord and outlet and it came back on ( no short cycle ).
Soooooooo This AM I go out and fire it up. Ambient around 72. Set tstat @ 65. Short cycled from get go!! About 15 seconds of compressor time ( cooling ), shutdown and repeat. Today, with voltmeter @ pod 20 amp breaker (during short cycle) - 118 rest. 114 when fan kicks on. 110 when compressor kicks in. Compressor runs for 15 secs and then shuts down. I went on to different projects, came back and put old tstat back on. Checked continuity of three tstat wires back to control box. Also double checked all connections from EasyStart wiring before starting up again. Turned it on auto with temp set @ 68 - of course it's working perfectly again!! So it wasn't shore power cord or voltage. It's not heat (ambient) related. I do need to check voltage @ compressor next. I think I'm going to contact some local HVAC guys tomorrow and see if I can talk them into climbing a ladder to check it out. Hopefully, it will short cycle while they are here!! f
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2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
|
fwunder
Senior Member Joined: 04 Oct 2013 Location: New Jersey Online Status: Offline Posts: 1676 |
Posted: 19 Jul 2021 at 11:52am |
Just to followup before HVAC tech arrives. I contacted local HVAC company. They reluctantly agreed to send a tech with no guarantee. I explained I just need someone to look at it and give me an opinion.
Anyway, short cycled on start this morning. One last check, I removed evaporator covering to inspect and check junction box wiring. All looks good. Of course, when I put it all back together AC is working great. LOL. Seems all I got to do is take something apart and put it back together, it works...for a little while. |
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2014 RPod 178 => MyMods and Buying Habits
2008 4Runner Limited 4.0-liter V6 Yes, those are wild ponies dining on grass while dumping tanks! |
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