Basement Air Problem

dflickinger · 05-08-2010, 12:59 PM

I have a 2005 Winnebago Vectra 40FD (4 slide). The Colman Mach 6537-671 basement air has never worked well since we first bought the vehicle.
There is a two speed Outdoor Fan on the unit. In 2007 we had to have the PC board replaced due to the fact the low speed OD fan quit working. I noticed at that time when they installed the new board that there was only 1 speed of the OD fan for both compressors now. The speed was slightly faster than the old low speed fan and the high speed setting was slightly slower than the old fan hi speed. At the time I determined that the maker has decided that the 2 speed fans were problematic and probably had decided to go with just one speed on the new boards. Since the ac unit is not working well (10 to 12 degree difference between intake temp and outflow ac) and the ac quality seems a little moist, could this be caused by the OD fan speed. Has anyone every had this happen to them. Could they have hooked the PC board up incorrectly. I have spoke to the manufacturer and they have never heard of it. We have suffered with this ac for 5 years now and we need to fix once and for all.

Thanks

smlranger · 05-08-2010, 05:59 PM

Have you checked the ductwork behind the rear cap of the motorhome to make sure it does not leak? This has been problematic on many Winnebago's. The duct will open at a seam and a lot of cold air can leak to the outside. You can use an infrared temp gun to check. Also, are you sure your second compressor is working?

Billy S · 05-08-2010, 09:24 PM

We have a 2004 Vectra with the same A/C, had the board replaced last year, the new board is wired a little differant than the old board, the ac was not working right and he changed the wiring and it works right now. I watched him make notes in the wiring diagram that came with the new board, I asked him if I could keep his notes, but he lost the paperwork.

DancinCampers · 05-09-2010, 10:14 AM

My guess is the board is not wired or operating correctly. The hi/lo fan speeds are in the motor windings, the board controls which winding is energized.

I would not think that having the outdoor fan on lo speed only would degrade indoor cooling except on very hot days.

If you have no air leaks in the ductwork, I would check the indoor coil for obstructions.

AFChap · 05-09-2010, 06:14 PM

The speed of the fan should not affect the outlet temp. It sounds to me like a classic case of having either just one compressor running, or more likely a separated duct behind the rear cap.

The first problem is very easy to check when running on 30a or generator. Watching the EMS amp readout, turn on the ac and set the thermostat at least 10 degrees colder than the temp reading. The first compressor kicks on and will pull about 16-18 amps. A minute or so later, the second compressor kicks on and will pull 23-25 amps. If you don't see somethign similar to those amp readings, something is wrong with one compressor.

A duct leak can normally be detected by checking the temp on the outside of the rear cap on a hot day and/or when the sun is shining on the cap. With the ac running full, check for cool spots up the passenger side, and y-ing off toward the driver side above the engine access door. You may even be able to feel cool air if you lay on the ground the stick your arms up behing the cap in the area of the duct.

Look at this discussion http://www.irv2.com/forums/f101/air-...ing-66106.html for some pics that will be a huge help in knowing what to look for relative to a leaking duct, and where to look for it.

dflickinger · 05-10-2010, 08:00 AM

Sorry, should have added that both compressors have been checked and are running and there are no leaks in the outflow venting as far as I can test without removing the rear cap.

These were all checked before I posted. I was hoping the single speed fan might have been a bigger problem than everyone thinks.

Grasping at straws at this point since no one who has worked on unit seems to fix the problem.

Thanks

AFChap · 05-10-2010, 04:42 PM

Quote:

Grasping at straws

Hmmm ...well, these units are sealed and supposedly "never need serviced" as far as coolant level is concerned. But I have read of some owners having fill valves added...

I see you say you have talked to the mfg'er ... does that mean you have discussed the problem and history with RVP in Wichita, Kansas?? If all the normal problems have been checked out and found not to be a factor, I think I would discuss it in depth with them to push for a solution. http://www.rvcomfort.com/rvp/contact.php

E-Mail [email protected] -- Phone (316) 832-4357

My unit works extremely well even in over 100 degree temps, with vent outlet temps below what most people believe to be possible. When they are working right, these units are great. They don't do service at the factory, but they can refer you to a competent trained service location. I have learned not to take mine to anyone not listed on the RVP website ...even Winnie dealers are not necessary competent to disagnose & repair the units.

KIX · 05-10-2010, 07:26 PM

Has anyone ever checked the return air plenum seal? If this seal was compromised the results would be less temp difference between return air and supply air. If outside humidity was high then your A/C would be working very hard to reduce indoor humidity.
I don't know how to tell you to check the integrity of the seal but I am experienced in replacing it on our coach. It's time consuming but not difficult

dflickinger · 05-11-2010, 09:23 AM

It is true that RVP states that these units are supposed to be maintenance free but what does one due when they are told that the unit is low on freon?

The answer is to installl "saddle taps" so that the freon can be charged.

I have spoken to RVP prior to posting. They seem to be nice but they are convinced that the unit could not be doing what I say.

I used RVP's suggestions as far as qualified repairman but it was several of those suggested repairmen that installed saddle taps which leaked and PC boards which have not worked correctly since they were first installed.

Maybe it is because I live in Florida, don't know.

The outflow venting was re-taped due to a leak but it did not help with the cooling problems.

I posted in the hopes that someone might have experienced the same problems as I but I guess not.

At RVP's and Winnebago's suggestion I will take the rig back to those same "qualified" individuals and let them take another crack at the problem at my expense.