Dometic A/C unit 13500 BTU model # 600315.321

by Dave
(Key West, FL)

Question:Monoco Knight Motorhome 2001. Front A/C unit works fine until it reaches the set temp then the fan shuts off but I keep hearing something running. It runs until the circuit breaker pops about 10 minutes. I suspect that it is the compressor that is running. After the breaker pops or if I shut it off before it pops, then turn the breaker back on the air works fine. I think the problem is in the relay control board part # 3107541.009.I can also pull the white plug out of this relay control box and my compressor shuts off. There is a relay in there that controls the compressor an N/O Relay K4 per the wiring diagram. The only thing is is that the diagram does not show how the coil of this relay is controlled. I cannot figure out from the wiring diagrams that I have if something else is causing this relay to stay closed. It just seems to easy to say the relay is just sticking and replace it.

Robbie:You have done an outstanding job in your diagnostics and have provided me the most valuable information ever to answer a question on my Web Site and I thank you.The problem your having is a common one and your correct in that the relay is sticking on your control board and you need to replace the board.The relay is controlled from the wall thermastat and is on your 12V system. You were also correct in saying the answer was just to easy and you have to replace the board. Have a Great day

Thanks for the Question Good Luck,

Comments for Dometic A/C unit 13500 BTU model # 600315.321

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Jun 02, 2013
Rv furnace
by: Dion

My rv furnace will not kick in when heat is required. I have to manually recycle power or adjust the thermostat slider down until I hear the relay contacts open and then slide it back up. It then heats up rv and shuts off. Changed thermostat already. It is the dometic 3107541.009 analog controls thermostat

Jan 31, 2015
compressor keeps humming
by: david

I have 1999 allegro bay motorhome. When we turn the ac on the compressor still hums even after shutting ac off. We have to turn the breaker off, to get it to stop. They sent us a replacement, part no 3313191.000 serial no. 43800933. Is this the right replacement part? Please help.

Jul 18, 2016
similar problem
by: Bill H

I have two a/c units. Front a/c was not working/starting,,,could get the fan to run but not the compressor. After several trys the compressor kicked in and worked great. I turned the a/c off, the fan quit, the compressor just hummed, had to turn the breaker off. Also with the front a/c running on fan only I can go to the rear unit, turn to fan only and the front a/c fan stops. Are they interconnected some how? Does the same 12v source power both control boards?

Jun 13, 2018
Compressor or Dometic RV A/C buzzing... NEW
by: greg

older Dometic AC, replaced on of capacitors in the AC, but, still buzzing, finally turned breaker off to Unit, Model 57915.331. Could it be the electronic board or a relay? Not sure what to do now

Aug 05, 2020
Duo-Therm model 600315.321/ Penguin NEW
by: Larry

This unit is installed on a 1999 Rexhall RV. When set to the low cool setting, the A/C runs well for about 2 hours then it starts to make, for the lack of a better term, pulsating humming noise and the fan (or air output) starts to slow down as well. On the higher setting (medium and High) the A/C unit starts to make this noise almost immediately and the fan speed seems to vary as well.

The same condition also happens when just running the fan with no A/C.

What are your thoughts?

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Robbie Warford, San Diego RV Repair

Hi, I'm Robbie. Welcome to!

Like the name implies, this site is all about helping you save money while keeping your RV in tip-top shape--and that is all about you having the knowledge to do so.

I've been a technician in the RV industry for 30 years, operating out of San Diego, California. And let me tell you, I love my job.

But I also love empowering RVers with the knowledge they need to make the right decision on repairs, or to make the fix themselves--and that, my friend, is the reason for this website. I hope you enjoy.

Or, learn more about me, my RV service practice, & this website here.