Coleman rooftop ac freezing

chart1 · August 01, 2013, 08:37:44 PM

My Coleman Mach3 rooftop is freezing up. Does it need charged? Cleaned? It blows out cold air until it freezes then air volume decreases and no cold air.

gus · August 01, 2013, 09:21:34 PM

Recharging would be my first guess. You must be in a high humidity climate.

luvrbus · August 02, 2013, 04:52:58 AM

I would go for the cleaning the filtration system on roof tops are not much they collect a bunch on the coils even keeping the filters clean pull the top cover you can tell in a hurry if it is a cleaning problem

rdbishop · August 02, 2013, 08:07:35 AM

Chart 1, Not to change the subject to much, but did you find your drivers window? If not , I have one in my wreaked MC-7. $250. plus shipping. I think the drip rails are the same also

Richard

TomC · August 02, 2013, 01:43:23 PM

Might need recharge. You can also try turning the thermostat down. Turn off the A/C and turn the thermostat all the way warm. Then slowly turn it until you here it click. Run it at that heat setting slowly cooling it down over the next couple of hours. If it still freezes up, probably needs a recharge. Good Luck, TomC

Dave5Cs · August 02, 2013, 02:08:24 PM

If you take the tops off be very careful. I pulled mine off a few weeks ago and both had huge wasp nests in them and darned if 1 hit me right between the eyes. Man that hurt.

Dave5Cs

Dreamscape · August 02, 2013, 02:11:48 PM

Sometimes our very old Dometic's will freeze if it's humid. Keeping the intake air filter clean is a must.

Of course, age might have been a determining factor for ours occasionally doing that. We just installed a new one in the bedroom, will see how that works out. In West Texas we have a dry heat most of the time.

Scott & Heather · August 02, 2013, 02:35:02 PM

Our Coleman froze up all the time until we stuck the thermostat freeze wire (copper) into the coils and completely solved the issue

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paulrobie · August 02, 2013, 03:09:17 PM

Also, make sure it is draining properly. I have had that issue where the water don't drain fast enough or at all. Water drains, problem solved.

luvrbus · August 02, 2013, 03:26:25 PM

I installed a Penquin 11 last year on the wife's little rig it will freeze up running on low with the least bit of dirt on the filters

Melbo · August 02, 2013, 07:32:09 PM

We just got back from the midwest and had to run the units on high at night to keep them from freezing -- on low they freeze up in the middle of the night and we had to turn one off and the other one on.

HTH

Melbo

Acausey · August 03, 2013, 01:38:49 PM

Had the same problem with the roof unit on my 5th wheel...turned out the cold air was not sealed off well and was leaking back to the return air intake. A roll of foil tape and a little red neck engineering and we never had another freeze-up!

~ Andy

chart1 · August 03, 2013, 01:50:09 PM

Seems like always a problem when I have the fan on low so maybe it is sucking the cold air back in the return air.

Seangie · August 04, 2013, 08:11:03 AM

Chart - I'm hanging with Mr. Scott Bennett this month (Berrien Springs MI if anyone wants to stop by) and speaking to him - he had the same problem (previously mentioned). It seems this is a common problem with this unit.

The 2 things he did to fix it were -
He moved the thermostat probe to the coils. So that the internal thermostat regulates itself from the temp of the coils and not the air moving through the unit.
2nd thing he modded was a divider between the exhuast air and intake air.

He has a single 13k unit that keeps the coach ice cold on a hot summers day now. He runs it all day on the lowest setting and it never freezes up.
Keep in mind that he has a ridiculously well insullated coach.

Pretty smart setup though.

-Sean

www.herdofturtles.org
1984 Eagle Model 10S