Winnebago Basement Air Conditioning - Page 2

MrTransistor · 06-01-2006, 04:56 PM

Hi FrontRangeRVer,

There are two thermistors used as temperature sensors, one attached to the outside coil and one on the inside coil. The outside thermistor is used when in heating mode and shuts down the compressors when there is a chance of the outside coils frosting over. The inside one is used when in cooling mode and does the same job of shutting the compressors off if there is a chance of the inside coil frosting over. These units have no defrost cycle.

I suspect that with an outside temperature of 75 degrees, your inside coil is down below 50 degrees and the thermistor is shutting down the compressors thinking there is a frost danger.

The inside thermistor on our coach worked fine but the outside one was tripping the compressors off with an outside temp of around 50 degrees. I added a resistor in parallel to the thermistor to bring the trip point down to around 33 degrees. (It's what I do.)

For others, the thermistor or control board will probably have to be replaced to correct this type of problem.

These are the specifications on the two thermistors, but owing to other circuit tolerances as well as defective thermistors, the temperatures could be way off from these values.

Inside Cooling freeze thermistor - Opens at 28 degrees +/- 3 degrees, closes at 55 degrees +/- 3 degrees.

Outside Heeting freeze thermistor - Opens at 18 degrees +/- 3 degrees, Closes at 38 degrees +/- 3 degrees.

Note: The thermistors don't actually open or close, they just change resistance with temperature.

FrontRangeRVer · 06-01-2006, 06:18 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MrTransistor:
Hi FrontRangeRVer,

There are two thermistors used as temperature sensors, one attached to the outside coil and one on the inside coil. The outside thermistor is used when in heating mode and shuts down the compressors when there is a chance of the outside coils frosting over. The inside one is used when in cooling mode and does the same job of shutting the compressors off if there is a chance of the inside coil frosting over. These units have no defrost cycle.

I suspect that with an outside temperature of 75 degrees, your inside coil is down below 50 degrees and the thermistor is shutting down the compressors thinking there is a frost danger.

The inside thermistor on our coach worked fine but the outside one was tripping the compressors off with an outside temp of around 50 degrees. I added a resistor in parallel to the thermistor to bring the trip point down to around 33 degrees. (It's what I do.)

For others, the thermistor or control board will probably have to be replaced to correct this type of problem.

These are the specifications on the two thermistors, but owing to other circuit tolerances as well as defective thermistors, the temperatures could be way off from these values.

Inside Cooling freeze thermistor - Opens at 28 degrees +/- 3 degrees, closes at 55 degrees +/- 3 degrees.

Outside Heeting freeze thermistor - Opens at 18 degrees +/- 3 degrees, Closes at 38 degrees +/- 3 degrees.

Note: The thermistors don't actually open or close, they just change resistance with temperature. </div></BLOCKQUOTE>

Thanks for this great info!!! I will pass this on to the service tech, as I think I told him that the outside Thermistor was the problem instead of the inside one....I think now they were right...Mark

FrontRangeRVer · 06-05-2006, 04:26 AM

I got my unit back from the dealer, and they moved the cooling thermistor to the outside of the inside coil for better air flow, and it appears to have solved the problem somewhat as now my basement air compressors run now when the OUTSIDE ambient temps drop below 75 degrees....The air flow out of the vents does appear to be somewhat weak, and the dealer says that also, and they believe the inside condensor will freeze up sometime especially since now the thermistor is now moved....I can live with that though...

Also, they replaced the automatic Electric transfer switch since it went bad...

All to the tune of approx $700 to be billed to Winnebago for warrantee repair.

Whew...NOW maybe after 4 months of ownership, and 3 months of it being in the shop, we can FINALLY actually enjoy this unit....who knows...I expect something else to break...

rebelsbeach · 06-05-2006, 04:38 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Also, they replaced the automatic Electric transfer switch since it went bad... </div></BLOCKQUOTE>

Seems to be a bad year for those for some reason,but I know Winnebago is aware of it,since several of them were iRV2 posters...

Fossilhog · 06-24-2006, 05:58 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Fossilhog:
Just an update, looks like it's going into the shop on June 20th. However with the help of RVguy who took the time to speak with me on the phone a few times and e mail me a service manual we decided to leave my fingers out of it at this point. I was able to bypass the thermister but that didn't seem to be the problem. I visual inspection of the control panel found a scorched wire from one of the compressor relays.

But thanks again RVguy and your phone number is on my redial. </div></BLOCKQUOTE>

So here's the latest.....the shop called me to say they are replacing the same things they replaced last October, Circuit board, fan blower motor and start capacitors. They called Coleman and asked for some insight as to the failure and was told probably low voltage condition. I run a volt meter plugged in the outlet within sight of my panel and have yet to see a low condition. Furthermore, I only used the unit once which was the Friday of memorial day weekend and it failed within an hour. Bottom line, x warranty is gonna bite the bullitt again. I'm supposed to get it back this week just in time for a July 4th week trip. I'll keep you posted.

Fossilhog · 06-30-2006, 08:51 AM

OK Just got it back, here's what they did:

Replaced Outside Blower Fan, compressor relay, blower motor capacitor and circuit board. Take your pick what was actually wrong. These extended warranties are great aren't they? I ordered a surge guard yesterday. We're off to Pa. West of the flooding!

Fossilhog · 07-06-2006, 06:26 AM

Just got bad from central pa. Here's the recap of the RV/AC debacle.

They only had 50 amp sites. I used the dog bone to power down to 120 vac. I got a 110 reading on my inside receptacles. Turned on the AC, it pulled 30 amps on my EMS meter. The EMS system shut down power to the water heater, fridge, fan motor speed and 2nd compressor (so it said). After a few minutes the EMS read 18 amps, and all the other power devices were reinstated although I kept the fridge on propane. The voltage remained between 108-110. If I ran on generator, all systems worked fine with a voltage reading of 125 VAC

My questions: was the "split" in the 50 amp service not enough to maintain enough current? Or was the voltage too low? I recall reading somewhere that you don't get a full 30 amps when splitting the 50.

Is 30 amps too much for the AC to pull. or was that just initial start up w/ 2 compressors. I believe reading the service manual it drops off the #2 compressor when certain requirements are met and maintains the temperature reading with #1.

I'm about to rewire my outside receptacle here at home with a 30 amp breaker and 10-2 wire.

I also got a surge guard at Camping World, arrived yesterday.

I presume the EMS was doing its job.

Comments?

Kiwi · 07-06-2006, 09:02 AM

A normal 50A RV outlet is 50 amps at 220 volts.

When split, this gives you two 50A @ 110 circuts. Only one of these would be presented to the dog bone.

When starting, the AC using both compressors can pull close to 30Amps. It should drop back to 24 or so depending on the head pressure (load). If your coach was hot and not down to near the thermostat setting then, it had a load.

If it dumped one compressor becaue it did not have enough current available, this could be due to an overloaded campground.

Just because a breaker is rated at 50A does not mean that 50A is available. It only means that a current draw above 50A will trip the load.

Your EMS could have sensed this by sensing the voltage drop as items were added to the load. In that case, the breaker did not trip, but you ran on one compressor.

Walt

Fossilhog · 07-06-2006, 11:23 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
When starting, the AC using both compressors can pull close to 30Amps. It should drop back to 24 or so depending on the head pressure (load). If your coach was hot and not down to near the thermostat setting then, it had a load.

If it dumped one compressor becaue it did not have enough current available, this could be due to an overloaded campground.

Just because a breaker is rated at 50A does not mean that 50A is available. It only means that a current draw above 50A will trip the load.

Your EMS could have sensed this by sensing the voltage drop as items were added to the load. In that case, the breaker did not trip, but you ran on one compressor.

Walt </div></BLOCKQUOTE>

Thanks Walt, so all was in order then. I just installed a 30A receptacle w/10 Ga wire and 30 amp breaker for the back yard. A/C starts at 27 on the scale then drops to 24 then 18. EMS not shutting down anything. I guess the key was wehn the generator ran everything fine.

FrontRangeRVer · 07-06-2006, 04:06 PM

Update on my original post.

We just got back from a 2,800 mile trip through some very hot areas, and the air conditioner coil didn't freeze up (even with the thermisor moved), and the compressors ran fine below the outside ambient temp of 70 degrees or so (original problem)....

With both compressors running while driving though some 95 degree heat with the generator running, the ambient INSIDE temp was only able to hold 78 degrees, and not drop lower than this. While this was fairly comfortable, the heat coming from the front windshield area is intense, and Winnebago should have accounted for this.

I do believe Winnebago screwed up with the heat load rating on this large motorhomes and actually undersized the basement air.....I checked and dont have a leaky rear duct problem that some have reported.

Kiwi · 07-06-2006, 05:46 PM

Actually a 17 degree drop from ambient with sun in the front window is great performance.

Did you run your dash air also? Did you try putting it on defrost and put the windshield fans on also if you have them?

Were you sure that none of the ceilinng vents were not directed on top of the retracted slide?

Walt

FrontRangeRVer · 07-06-2006, 06:08 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kiwi:
Actually a 17 degree drop from ambient with sun in the front window is great performance.

Did you run your dash air also? Did you try putting it on defrost and put the windshield fans on also if you have them?

Were you sure that none of the ceilinng vents were not directed on top of the retracted slide?

Walt </div></BLOCKQUOTE>

Walt...these are all good questions.

I measured 55-60 degrees out of the roof front vents (while driving using my laser temp gun). The return air at the base of the bed was 75-80 degrees....So the air conditioner was working correctly.

I did run the dash air while driving to compliment the basement air during the hottest outside temps, then shut it off during hills, etc.

I did not use the dash fans, and had all roof vents aimed forward toward ME...lol

78 degrees at the thermostat is the best this unit can do while driving though mid 90's...and thats with the fan on "On", and starting out with the setting on 72 degrees in the morning.

I'm not totally complaining, although I believe it is slightly undersized for these bigger coaches.

When we stopped at an RV park with outside temp of 87 degrees, and put out all three slides, the inside temp actually went UP to 80 degrees for a couple of hours as the chassis and slideouts were HOT....Both compressors were running with output of 55-60 degrees from the farthest roof vent.

Kiwi · 07-07-2006, 08:57 AM

One more thing....

When is the last time you changed your filter?

Walt

FrontRangeRVer · 07-08-2006, 07:32 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kiwi:
One more thing....

When is the last time you changed your filter?

Walt </div></BLOCKQUOTE>

Never...bought this unit new 6 months ago...this is the first trip with the air running

The Clock Meister · 07-08-2006, 08:26 AM

Having just yesterday spending over 5k for a new AC unit for the stick home partly due to the previous owner not keeping the filters changed, I am going to be ever more vigilant about changing them in the MH and stick house now.

The tech and I talked some about the basement air in the MH and he said that with that type of system it is even more important to keep the flow at maximum and that a little dirt on the evaporator coil will greatly impede the performance of the system. Changing the filters monthly costs less than $5.00 and is sure worth it if it makes it more comfortable and avoids any service problems down the road.

My two cents, for what it is worth!

Chris

ichn2go · 07-08-2006, 09:56 AM

You had better check the filter, when you run the heat it uses the same filter. Look at it once a month ,, if it needs it change it. At least you know its clean and you are getting maximum flow.

The cheap filters are recommended for more air flow and the arrow should point down. Good Miles

wagonmaster2 · 07-09-2006, 07:58 PM

FrontRangeRver -
Been traveling for 7 weeks so just read your post. My 2004 Meridian has had the same problem with intermitent compressor running with outside temp below 75 degrees since it was new. Last November I had it at Forest City for several warranty problems, so they worked on this problem also. Said they had it fixed but in June while in Colorado with outside temp around 70 - 72 and inside temp at 78, the compressors did the same old thing. I'm going to call them this week and see what their response will be, but since I'm now out of warranty I'll probably get nowhere. Hopefully due to your solution maybe if I pass it on to them I'll get some help other than "take it to your local dealer", which is no help at all and the reason I was in Forest City.
Wagonmaster
2004 Meridian 36G

FrontRangeRVer · 07-10-2006, 02:58 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by wagonmaster2:
FrontRangeRver -
Been traveling for 7 weeks so just read your post. My 2004 Meridian has had the same problem with intermitent compressor running with outside temp below 75 degrees since it was new. Last November I had it at Forest City for several warranty problems, so they worked on this problem also. Said they had it fixed but in June while in Colorado with outside temp around 70 - 72 and inside temp at 78, the compressors did the same old thing. I'm going to call them this week and see what their response will be, but since I'm now out of warranty I'll probably get nowhere. Hopefully due to your solution maybe if I pass it on to them I'll get some help other than "take it to your local dealer", which is no help at all and the reason I was in Forest City.
Wagonmaster
2004 Meridian 36G </div></BLOCKQUOTE>

Mine seems to work well with the moving of the thermister....

wagonmaster2 · 07-10-2006, 10:48 AM

FrontRangeRver-

Did you by any chance see them move the thermister? Or where it is actually located? Is this difficult to do? Will it require any disassembly of the air unit? I may have to use a local repair shop that may not be familiar with the basement units. Thanks for all your responses.
Wagonmaster2

FrontRangeRVer · 07-10-2006, 11:53 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by wagonmaster2:
FrontRangeRver-

Did you by any chance see them move the thermister? Or where it is actually located? Is this difficult to do? Will it require any disassembly of the air unit? I may have to use a local repair shop that may not be familiar with the basement units. Thanks for all your responses.
Wagonmaster2 </div></BLOCKQUOTE>

They moved the inside thermister from one side of the coil (the inside coil,under your bed) to the filter side of the coil and its laying now against the coil where you can see it when you remove the filter. Im not sure, but I THINK they had to drop the unit to get at this thermister.

Im wondering if you bypass this thermister, if it wouldnt do the same thing....I am not having a freezing coil problem either...

Oh well...this has totally repaired the problem as I can have both compressors running now at any outside temp below 70 degrees where as before I could not get them to stay on below these outside ambient temps.

I have heard other Winnies having the same problem....We found a Winnebago tech (from our dealership) who was willing to try this as he believed it would work, and it did....no thanks to RVP....

You should tell your dealer to move the inside thermister to the other side of your coil....