Winnebago True Air

FrontRangeRVer · 01-16-2006, 03:11 AM

We have a new MH, and I was trying to test all our equipment, and as I was testing our air conditioner, I could only get our compressor to come on for about a minute, then it would shut off. The ambient outside temperature was 53 degrees, and I moved the thermostat down to about 45 degrees.

Is there an outside ambient temperature "cutoff" point where the air conditioner compressor wont run?

I COULD get the Heat Pump to run, but not the air conditioner.

FrontRangeRVer · 01-16-2006, 03:11 AM

We have a new MH, and I was trying to test all our equipment, and as I was testing our air conditioner, I could only get our compressor to come on for about a minute, then it would shut off. The ambient outside temperature was 53 degrees, and I moved the thermostat down to about 45 degrees.

Is there an outside ambient temperature "cutoff" point where the air conditioner compressor wont run?

I COULD get the Heat Pump to run, but not the air conditioner.

rebelsbeach · 01-16-2006, 04:20 AM

Thinking you are trying to get the heat on,you might look near your panel for an "LP Cutoff" switch....My coach heat did the same thing until the nice folks on this forum reminded me of the LP cutoff switch....Mine was on the monitor panel wall.

ON EDIT: I see you said air conditioner as you were "testing" it,but you still may run into the LP issue...

rebelsbeach · 01-16-2006, 04:29 AM

Looks like someone answered your question over on rv.net....

Hikerdogs · 01-16-2006, 04:34 AM

FrontRangeRVer: I think the AC has a minimum operating temperature of between 55* & 60*. Once the coach is cooled to that temperature there isn't enough differential between the inside & outside air for the unit to provide any cooling effect.
The heat pump is actually the AC system running in reverse. The condenser becomes the evaporator and the evaporator becomes the condenser.

Here's a simplistic explanation of how the system works. When the system is run in the AC mode the compressor compresses the "Freon" from a low-pressure gas to a high-pressure gas. As the gas passes through the condenser (on the outside of the coach) the heat is expelled to the atmosphere through the cooling fins and the gas turns to a liquid. The high-pressure liquid passes through the lines to the evaporator in the coach. The liquid the goes through a metered orifice at the inlet of the evaporator. As the liquid passes through the orifice it expands and returns to the gaseous state. As the name implies the evaporator changes the coolant from a liquid to a gas. As coolant expands it cools the coils on the evaporator. A fan blows across the coils and transfers the cool air into the coach.

When you run the heat pump the evaporator and condenser change duties. The heat generated by compressing the coolant is expelled in the coach and the expanding gas cools the condenser on the outside of the coach. That's why the heat pump only works until temperatures get down to the high 30s. If it were to try to run at lower temperatures the condenser would frost over and eventually freeze up. If it does freeze the flow of coolant would be blocked & either starve the compressor, or over pressure the system.

So basically I'm trying to say that if your heat pump works the AC is working. You'll have to wait for a warmer day to try it in the AC mode.

FrontRangeRVer · 01-16-2006, 05:38 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rebelsbeach:
Looks like someone answered your question over on rv.net.... </div></BLOCKQUOTE>

No they didn't....I'm looking for Winnebago owners comments and suggestions.

FrontRangeRVer · 01-16-2006, 05:40 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Hikerdogs:
FrontRangeRVer: I think the AC has a minimum operating temperature of between 55* & 60*. Once the coach is cooled to that temperature there isn't enough differential between the inside & outside air for the unit to provide any cooling effect.
The heat pump is actually the AC system running in reverse. The condenser becomes the evaporator and the evaporator becomes the condenser.

Here's a simplistic explanation of how the system works. When the system is run in the AC mode the compressor compresses the "Freon" from a low-pressure gas to a high-pressure gas. As the gas passes through the condenser (on the outside of the coach) the heat is expelled to the atmosphere through the cooling fins and the gas turns to a liquid. The high-pressure liquid passes through the lines to the evaporator in the coach. The liquid the goes through a metered orifice at the inlet of the evaporator. As the liquid passes through the orifice it expands and returns to the gaseous state. As the name implies the evaporator changes the coolant from a liquid to a gas. As coolant expands it cools the coils on the evaporator. A fan blows across the coils and transfers the cool air into the coach.

When you run the heat pump the evaporator and condenser change duties. The heat generated by compressing the coolant is expelled in the coach and the expanding gas cools the condenser on the outside of the coach. That's why the heat pump only works until temperatures get down to the high 30s. If it were to try to run at lower temperatures the condenser would frost over and eventually freeze up. If it does freeze the flow of coolant would be blocked & either starve the compressor, or over pressure the system.

So basically I'm trying to say that if your heat pump works the AC is working. You'll have to wait for a warmer day to try it in the AC mode. </div></BLOCKQUOTE>

Thanks for the help! I was thinking there might be a ambient temperature cutoff point to the compressor, so since the outside temperature was around 53 degrees, the compressor wont run (or start then stop immediately as it did in my case).

rebelsbeach · 01-16-2006, 05:45 AM

From rv.net in fewer words.....

Posted: 01/16/06 08:21am Link | Quote | Print | Notify Moderator

--------------------------------------------------------------------------------
There's no way your AC could pull the inside air down to 45. Seems that it's working OK to me. The heat pump portion, however, will function as you said.
------------------------------------------------
charles weidman

FrontRangeRVer · 01-16-2006, 05:48 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rebelsbeach:
From rv.net in fewer words.....

Posted: 01/16/06 08:21am Link | Quote | Print | Notify Moderator

--------------------------------------------------------------------------------
There's no way your AC could pull the inside air down to 45. Seems that it's working OK to me. The heat pump portion, however, will function as you said.
------------------------------------------------
charles weidman </div></BLOCKQUOTE>

Hikerdogs was a big help and might have hit the nail on the head. There might be an ambient temperature cutoff for the compressor to run or not run.

The above reply from the other website (and the LP one) is not the answer that understood what I needed. I said I moved the thermostat to 45 (just a number below the ambient temp of 55) to get the compressor to run....it could have been set to 52 or so....I had no intention of cooling my RV to 45....I just wanted the compressor to run.

rebelsbeach · 01-16-2006, 06:20 AM

Sorry...I had posted the lp answer and then went back and reread your original post,which I indicated my mistake on edit.

Glad you apparently found your answer...moving on now.

John_Canfield · 01-16-2006, 09:29 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FrontRangeRVer:
Is there an outside ambient temperature "cutoff" point where the air conditioner compressor wont run? </div></BLOCKQUOTE>Be aware there is also a temp where the compressor won't start in heat pump mode. On my coach it is about 42-44 degrees outside air temp.

FrontRangeRVer · 01-16-2006, 10:20 AM

Good info. Thanks!

DancinCampers · 01-16-2006, 06:27 PM

Hikerdogs is on the right track, but the unit is not controlled by ambient air temp, but rather coil temp. My schematics show that the cooling freeze thermister, T14 & T15, will open at 28 deg F +/- 3 deg, and close at 55 deg, +/- 3 deg. (actual coil temp).

If the air flow over the evaporater (Indoor coil in cooling mode ) is lower than 55 deg the thermister will not close and let unit run.

The thermisters are attached (in contact with) the coils. The heat pump thermisters are attached to the outside coil & act in a similar manner.

wagonmaster2 · 01-17-2006, 08:27 PM

I had somewhat the same problem on my 2004 Meridian, the air conditioner would't keep running (would cycle on & off every 4-6 minutes) if outside temp was lower that 72-76 no matter what the inside temp was. Had it checked in Forest City in November when I was there for other work and they found a defective sensor at the condensor. They said it was there to keep the coils (I guess evaporator coils) from freezing up. Haven't been able to test it yet with temperatures in 30's & 40's but hope they were right.
Wagonmaster2