A/C Freeze Guard - Montana Owners Club

campbud · 05-09-2005, 08:37 AM

I have a question about the freeze guard on the air conditioner. How do you know that it is working correctly?

We had some 80 degree weather and so we tired the air. I didnt feel like it cooled the rv like I thought it should. It seem to kick off and on like it should but just never felt cold. Also should you run the a/c on low or should it always be on high? Thanks everyone!

Montana_2779 · 05-09-2005, 10:26 AM

We've always run our unit on high for two reasons: 1) it seems to be the common theme that the unit will be less likely to freeze on this setting, and 2) it seems to produce the best cooling air on this setting. This is our second Coleman unit, and we've had little trouble with either using the high fan setting. In our case (southeast Texas swamps), the unit has performed marvelously at 80+ degree temperatures.

Our unit has only been finicky under one specific condition: if the A/C stops and we don't give it a 10 minute "cool down" period before lowering the thermostat, the A/C will trip its breaker (the 10 minute cool-down rule seems to be pretty standard for all types of A/C per my A/C guy at work). HOWEVER, during warmer days, the A/C will cycle on and off on its own (no t-stat adjustment), often turning back on just a few minutes after it shuts off, and the breaker is fine! Go figure (if anyone has a good answer for this, I'd love to hear it).

sreigle · 05-09-2005, 03:21 PM

Bob and Kathy, the DuoTherm AC units seem to be prone to freezeup when run on low fan in high humidity situations. Not always, but sometimes. This has happened with DuoTherm AC units for as long as I can remember. The solution is to run it on high fan in those situations. If you do experience a freezeup, the air will not be cool and may feel warm. You can let it sit for awhile, maybe 30 minutes or an hour, to let it thaw out. We've had fifths with Coleman AC units and never had that problem. If I had a choice I'd go with a Coleman but both our Montanas came with DuoTherm. They do a good job, just a pain when they freeze up.

Pete, I don't ever recall tripping a breaker in that situation. I have to wonder what your AC guy was thinking about. Maybe I've just never seen it but that seems a bit odd to me. If it's tripping the breaker it's drawing too much amperage at startup. Maybe someone with more electrical knowledge than I have can help us out here.

RMccord · 05-09-2005, 04:03 PM

Well I have a question. I live in So. Cal. not humid by nature. We will be traveling for a couple of weeks in August thru Colorado, South Dakota and Wyoming. I do not anticipate these will be too humid either. But I do anticipate that I will be running the A/C allot during the stays. We only plan one hotel nite on the way to Rapid City in Denver. Should I anticipate these units freezing up? Sounds like a bummer. If they do they don't drip into the trailer do they? I would think not. Sorry for that pretty dumb quesiton.
Would we be wiser to put a bedroom unit in and alternate between the two?
Or will it be pretty unlikely to do so when using a digital thermostat. Also would a couple of small fans used to move the air around a bit help the A/C avoid this?

Thanks
Totally inexperienced in this area.

Bob

fulltimedreamer · 05-09-2005, 07:15 PM

Bob,
I don't think the freeze-ups are something that's going to be a big problem. We have used ours in Georgia and Florida extensively and have not had a freeze-up. We usually run the fan on high. In fact when I changed from an analog thermostat to a digital I didn't even connect the low fan speed connection. In high humidity situations (read Georgia in August) you need to run the fan on high.

mazeeff · 05-10-2005, 01:38 AM

The 2005's have freeze guard and it works quite well. A simple test can be performed to tell if your unit is cooling properly. Take a digital temperture probe, and measure the outlet temp on the A/C. It should be 20-30 degrees cooler than ambient. Also, I would remove the filter grate and look at how the ducts are sealed. Quite often they are not sealed correctly, and this results in your cold air being re-cycled through the A/C unit, and/or pumped into the attic. What size unit do you have?

campbud · 05-10-2005, 03:33 AM

Mike I am looking for my digital temperure probe now and will try this. I will also look at the filter grate. Now if I could just find that dang probe! Thanks Bob

mazeeff · 05-10-2005, 05:40 AM

Quote:

quote:Originally posted by campbud

Mike I am looking for my digital temperure probe now and will try this. I will also look at the filter grate. Now if I could just find that dang probe! Thanks Bob

While your up there with the filter grate off, take a look at the freeze gaurd probe, and make sure that it is inserted into the evaporator coils, and has not fallen out. It is a long black plastic coated probe that slides into the coils. It might be inserted from the inside or outside of the coils. If it is on the outside, you have to remove the roof housing to see it. If your unit is cycling, then I would not expect freeze up as the issue. One easy way to check for freeze up, is for someone to stand outside, and watch for run-off after the unit cycles off. If it is freezing, a LARGE amount of water will run off the roof, instead of the normal dripping. The ice thaws very quickly, and a gush of water off the roof is the result!

mazeeff · 05-10-2005, 05:41 AM

Also, are you using the "quick cool" feature of the unit? If you open the "quick cool" grates, the unit operates more efficeintly, due to the fact that is less restriction to the cooler air coming from teh unit.

mazeeff · 05-10-2005, 05:46 AM

As far as temperture probes go, I use a cheap ($20) wireless set I bought from Walmart. I hang the wall unit on the wall, and use the wireless pod to test A/C, Freezer, outside temp as required. This way, you can simply sit the pod up inside the filter grate, and watch the difference on the wall unit. I normally leave the pod in the freezer to prove that the fridge is cooling properly.

sreigle · 05-10-2005, 05:58 AM

Bob (RMccord), I agree with Lamar on this. And I didn't mean to get you too concerned. The freezeups do not happen frequently. If you are in high humidity, just run it on high fan. I've never had a freezeup on high fan.

Your question is not dumb at all. If you don't know the answer, then it's a legit question. If the AC unit freezes up, it could drip into the coach during the thawing. I've not seen that but others have reported it happening. Again, freezeups are pretty rare and are not at all likely to happen. I've only seen it in hot, high humidity situations with fan on low speed. And then only rarely. I've never heard of anyone having to add a window AC to a Montana.

I would not be concerned about the AC unit. We use our AC a lot. We lived for years in NE Kansas, a very high humidity area. As fulltimers we are all over the country. The only two freezeups I can recall came in NE Kansas. Letting it thaw and then switching to high fan took care of the problem. If I were you I'd not worry about it. I'd just be aware that if the AC unit starts blowing warm air you'll know why and to shut it down and let it thaw out. Again, it's very unlikely you'll encounter this.

Mike mentioned the freezeguard protection on the 2005 models. I was not aware of that. So all of this may be moot. You may never see a freezeup on yours if freezeguard really works.

As for the fans, we do use a fan in the bedroom area and in the living area. It's not to help out the AC but to help circulate the air. Or if we just don't think it's warm enough to run the ac or we want to have windows and doors open, etc.

Good luck. Sounds like a nice trip you have planned.

mazeeff · 05-10-2005, 06:06 AM

Quote:

quote:Originally posted by sreigle

Mike mentioned the freezeguard protection on the 2005 models. I was not aware of that. So all of this may be moot. You may never see a freezeup on yours if freezeguard really works.

The freeze guard on the new units works quite well. I forced mine to freeze up just to test the option, and it worked great. The way I made it freeze up, was to simply block off the exit vents on the ceiling unit, which forced the cold air back into the return. It took about 3 minutes for the coils to freeze up. Once the probe read 32 degrees, the unit turns off the compressor, and puts the fan on high. The freeze thaws, and the compressor turns back on. I really think it eliminates the freeze potential!

Montana_2779 · 05-10-2005, 06:11 AM

Agree with Steve. Freeze-ups are fairly rare, even in these sub-tropical (VERY humid) conditions. All suggestions above will lead you in the right direction. Spoke again with our A/C tech here, and he suggests that the breaker situation is not really an issue. The unit has probably not had time to settle and re-bablance the high and low-side pressures (which will create a higher amperage load on compressor startup). As the unit (didn't realize it was a Duo-Therm! Should go back and read my books!) has no other issues, this has been of little real concern. We've been very pleased with the cooling capacity of the one A/C (originally wanted two, but the rig we bought off the lot didn't come that way). Kudos to the manufacturer and Montana (Mountaineer assy line) for the buid and installation.

jpkelpe · 05-10-2005, 07:30 AM

Bob--(RMccord) You will find that most of the time in Colorado, Wyoming and South Dakota, especially the Black Hills you won't even need the air conditioning at night because of the low humidity and nights get cool--you might even need a jacket once the sun goes down. It can get Hot in the daytime in Wyoming, especially the part between Denver and Rapid City, but the nights are cool.

sreigle · 05-11-2005, 10:38 AM

Pete, thanks for the excellent explanation.

NJ Hillbilly · 05-11-2005, 01:15 PM

Another reason to run the fan on high is the fact that there is only 1 blower motor. This motor runs the fan that circulates the cool air inside and runs the fan on the condenser on the outside. Stick homes have seperate fan motors so speed is not an issue.

The more air that is pulled across the condenser, the better it will cool.

John

sreigle · 05-11-2005, 02:53 PM

Welcome back, NJ Hillbilly. Haven't seen your name on here in awhile.

azstar · 05-11-2005, 04:46 PM

Hi Folks,

Here's my question,

I seem to remember hearing somewhere, maybe on this Forum, that when in high humidity and high Temp. it was recommended to put the fan on manual and high so the fan runs continually but the compressor is alowed to cycle to keep from freezeing up.

It this good info.?

Thanks

NJ Hillbilly · 05-12-2005, 02:49 AM

Thanks Steve, I've been really busy working, lurking from time to time, and I am in the process of buying a new stick home, You know how that goes.

Nice to be missed,
John

Montana_2779 · 05-12-2005, 04:02 AM

Azstar, I've heard exactly the same thing from the tech who installed the Coleman on our pop-up a few years back. He indicated that this method would curtail freezing, same as your info. Looks like we have third-hand confirmation.

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