Dometic Basement Air/// basement unit not working

[Richard and Rhonda]

One of my basement airs was not blowing cold air. The fan in the coach was running but no cold air. The unit in the basement does not come on. I do not have voltage at the black and white 120 service at the basement unit. The breaker is not tripped in the breaker box in the rear of the coach.

Any ideas on where to start? It's the front one if that makes any difference.

The lovely bride says this in numero uno priority. Gotta have AC in Tejas.

[Richard and Rhonda]

This is what I have learned so far, just in case you have to investigate a similar problem in your coach.

The main control board for the Dometic units is usually located in close proximity to the evaporator (the unit inside the coach) For my front unit, the evaporator is right by the door, underneath the kitchen counter. When I removed some of the internal pieces of the cabinet, I found a small box with the control board inside. On the control board is a relay the provides power to the condenser unit. This relay is not "making". When I bypass the relay and hardwire power to the condenser, it works as it should.

Here are some other useful bits of info.

My Dometic systems are filled with R22. I took these measurements at about 55 degrees ambient. The static pressure in all three units was about 90 psi. When running the high side was about 150 and the low side about 45.

I have to find a replacement board now.

[fulltiming]

Richard, trying to find a replacement board may be a bit of a chore since Dometic doesn't make our type of units any longer according to the folks at Newell. You may be able to find someone that is good at electronic troubleshooting that can go through your board and locate the defective components and replace them. I have found a guy in Yuma, AZ that was able to get one of my basement A/C's working after several others had failed.

I understand that you have determined that one or multiple relays on your board are fried. Hopefully, replacing those relays with good ones will solve your problem.

[Richard and Rhonda]

Yep, you're right. Obsolete, no longer available. Dometic says the only fix from their end is a replacement control box and thermostat. About $200.00. I think I will try some new relays first and see if that works.

For info the new control box is Dometic part no 3109226.005 and the thermostat 3109228.001

[fulltiming]

Thanks for the part numbers Richard. I will add that to my parts list information. $200 is cheap compared with replacing the entire unit with a new 14K BTU Dometic CruisAir unit although I do like the digital thermostats available with the CruisAir.

[Richard and Rhonda]

I determined the relay on the board was bad. Ordered one for about 7 bucks, and replaced it. Works great now.

I pulled the relay part number off the top of the relay, googled it, and ordered from an online components supplier.

If you haven't replaced thingies on a printed circuit board, it really isn't that hard. You need a small soldering iron, and solder wick. Solder wick is braided copper wire. You use it to wick the solder off the joint. That way the component will come right off the board. Put the new piece in, hit it with the iron and a little solder, and you are in business.

[larryweikart]

There is a gentleman located in Elkhart In. who was with Dometic for many years before starting his own business. He has a wealth of knowledge about the a/c system used on the Newell and has helped me thru my problems. The split air system used in the 90's is obsolete and creates a major problem if it should ever need to be replaced. Thankfully, Newell has located a source for replacing the compressor if needed as one of mine did. This mans name is Dave Holmes, "Holmes on Wheels" phone #574-266-1586. Definitely a number to keep on your cell. :roll: javascript:emoticon(':D')

[larryweikart]

There is a gentleman located in Elkhart In. who was with Dometic for many years before starting his own business. He has a wealth of knowledge about the a/c system used on the Newell and has helped me thru my problems. The split air system used in the 90's is obsolete and creates a major problem if it should ever need to be replaced. Thankfully, Newell has located a source for replacing the compressor if needed as one of mine did. This mans name is Dave Holmes, "Holmes on Wheels" phone #574-266-1586. Definitely a number to keep on your cell. :roll:(':D')

[Richard and Rhonda]

Thanks Larry, great post!!!!

Just for info, do you remember the source and part no for the compressor? And when you replaced the compressor, did you stay with R22 or convert to R135a?

[larryweikart]

Sorry for the delay Richard, been at a race track without internet service. Must get a dish to correct this problem. I do not have that info with me but can send it to you in 2 weeks when I get home. I went to Newell factory and actually drove to Joplin to get the compressor which they then installed. I have not changed from R22. All 4 airs are now working properly. I also purchased an extra compressor just in case they become difficult to locate.