BMC Front Air Question

[slckpurdy]

Driving my coach BMC 1994 back from upper Michigan and the front air started blowing hot air. I understand there were issues with the Cab air on these units. Tried to run the roof air and generator but it was almost 90 and we were roasting. It didn't help when someone with a RV lost it on the expressway and we went threw a detour off the X way which all in all took 2 1/2 hours v/s the 40 minutes we were away form home. Any suggestion where to start? With the generator underneath, you in the cab and the sun beating down I thought I was in an Easy Bake Oven.

[fxdwg]

Steve,

Sounds like she lost her freon. I'll admit the roof airs don't work all that well when you're sitting in the front seats, especially if you're headed into the sun. Check to see if the compressor clutch is kicking in. It's possible it only lost a high pressure or a low pressure sensor, but I'm betting it's freon related. Depending on how yours is set up, you could have also lost vacuum. This could allow the heat/no heat door to have flipped to heat and caused you to get the hot air, even though the AC is fine. Check to see that at least the dash controls cause an action on the heater/AC doors. Let us know what you find. Having the dash air makes a HUGE difference in the comfort of the front seat occupants. At least it does for me. I can actually get the front seats cool enough to not sweat in 100 degrees and headed south into the sun weather now that mines currently working. Hopefully I can get a year out of it. If I have to recharge yearly, I think I can tolerate that, given the benefits I get.

[AC7880]

Steve,

As step 1 I suggest turn on the cummins and the AC on the dash. Open the furthest rear passenger side lower door and make sure the AC condensor fans are running. On mine, the relay was toast and the fans weren't turning. I fried the compressor due to overheat. Open the rear hood and make sure the AC compressor is turning freely, and belt appears to be adjusted with no slippage (of course keeping hands free of belt and plulleys).

If it is not a easy fix on the dash air, then for my level of AC repair knowledge I head to a qualified shop.

The next step is to improve the cooling you get with or without the gen running and roof ACs on. With gen/roof air I point the vents forward on both ACs, and next you need fans blowing that cold air around. The previous owner had 2 110 volt fans set on the floor behind driver and passenger blowing upward on them. I used that the 1st year and it really helps.

After that 1st year, I mounted 2 12 volt fans on the overhead, one pointing at driver, 1 at passenger. I mounted a master on/off for them on dash in front of driver, to able to turn on and off on the fly. Advantage is I can use them whether I run the gen and roof airs or not. Each fan can also run on hi, low, or be off w switch on the fan. This has been the best answer for our comfort on the road. I rarely run the dash air anymore, when the fans aren't enough, the gen and roof airs come on w 12 volt fans also on.

From a older post cut and pasted to here: I installed 2 each two speed above the dash hanging down from overhead cabinets 12 volt blower fans with on/off switch in dash so I can operate them while driving, and this helps a LOT running down the road. I wired the power for the 2 fans into front lower compartment wire# 4, and grounded them at right front clearance light.

A couple of pic that have the 12 volt fans showing at: http://good-times.webshots.com/photo...28993757kDDlhY

http://good-times.webshots.com/photo...28993757QRKqCg


A thread on BMC dash air is at: http://www.wanderlodgeownersgroup.co...ead.php?t=2768

Originally Posted by slckpurdy

Driving my coach BMC 1994 back from upper Michigan and the front air started blowing hot air. I understand there were issues with the Cab air on these units. Tried to run the roof air and generator but it was almost 90 and we were roasting. It didn't help when someone with a RV lost it on the expressway and we went threw a detour off the X way which all in all took 2 1/2 hours v/s the 40 minutes we were away form home. Any suggestion where to start? With the generator underneath, you in the cab and the sun beating down I thought I was in an Easy Bake Oven.

[iamflagman]

Originally Posted by AC7880

The next step is to improve the cooling you get with or without the gen running and roof ACs on. With gen/roof air I point the vents forward on both ACs, and next you need fans blowing that cold air around. The previous owner had 2 110 volt fans set on the floor behind driver and passenger blowing upward on them. I used that the 1st year and it really helps.

After that 1st year, I mounted 2 12 volt fans on the overhead, one pointing at driver, 1 at passenger. I mounted a master on/off for them on dash in front of driver, to able to turn on and off on the fly. Advantage is I can use them whether I run the gen and roof airs or not. Each fan can also run on hi, low, or be off w switch on the fan. This has been the best answer for our comfort on the road. I rarely run the dash air anymore, when the fans aren't enough, the gen and roof airs come on w 12 volt fans also on.

From a older post cut and pasted to here: I installed 2 each two speed above the dash hanging down from overhead cabinets 12 volt blower fans with on/off switch in dash so I can operate them while driving, and this helps a LOT running down the road. I wired the power for the 2 fans into front lower compartment wire# 4, and grounded them at right front clearance light.

A couple of pic that have the 12 volt fans showing at: http://good-times.webshots.com/photo...28993757kDDlhY

http://good-times.webshots.com/photo...28993757QRKqCg


A thread on BMC dash air is at: http://www.wanderlodgeownersgroup.co...ead.php?t=2768

For the benefit of those owners that have older 'Birds that are reading this thread and like mine either don't have the engine operated dash air conditioner in operating condition, or in my case it has been removed after being too costly to repair and or maintain, plus I'm not a fan of just cooling the front portion of the 'Bird, if I want to stop all of a sudden to take nap or go back and eat something, I don't like waiting to let the back area cool down, so I run the genset and turn on as many of the three roof airconditioners that it takes to maintain the temperature where I like it to be. This also exercises the generator, which in my opinion is needed in most the 'Birds that I have seen that have very low generator hours, which I don't think is doing them any good not being used.

I also do just what Dan does but with the older models you can aim that front roof airconditioner directly at the Dash/Overhead air intake for the Dash Air system, then use the Dash Air Fan switches for the driver and passenger, in conjunction with the roof airconditioner switches which in my case are located to the left of the drivers seat, to control the temperature, usually once the cabin temperature gets cold enough for me, I can get by just using the center roof airconditioner and then if it starts to heat up again, I just flip on the switch for the front Roof Airconditoner.

http://www.pbase.com/iamflagman/image/99578822

http://www.pbase.com/iamflagman/image/99578821

This has worked great for me and only seems to not be as efficient when the sun is low on the horizon and the ambient temperature is hovering near 100 plus degrees outside, plus I need to work on making a better seal on my doghouse cover to prevent 180 - 200 degree hot air being blown on my right leg when the Horton fan kicks in, I have some new gasket material that Bill Garamella gave me to install there and hopefully that will improve things. Mine also has the two additional 12 volt fans mounted near the center of the overhead compartment, but mine are only controlled by the switches on the fan and I can't find the circuit or where the wiring for them goes so that I can mount a more convenient switch to turn them on and off with, as it is now if I don't remember to turn them on before I put on my seat belt and pull out on the road, they very seldom get used, but they may make a little difference when the ambient temperature gets real hot outside and that afternoon sun starts to really heat up the drivers area, overall though this setup has worked the best for my conditions.

I realize that those members that have working Dash Air systems are happy with the performance of them, but this is an alternative if it is needed, in my case Randy and I looked it over and saw a very expensive repair job at hand to get it back into working order and I saw a need for an additional 4 inch air intake for my CAT 3208NA and the area where the A/C Compressor used to be is now used for just that and while I have no test proof to back me up, I believe that especially on a engine like mine that the horsepower gain by not using the A/C compressor, which is probably similar to what happens when the Horton Fan kicks on and off and I have used the override switch for that to help slow the coach down, but using the generator instead is significant and the fuel mileage is probably very similar, so I'll take the Horsepower gain myself, just ask those members that have run with me while I'm towing my trailer, my little 210 HP CAT 3208NA does perform very well, just don't mention or even whisper the word SHHHHH..........hill...or even then it will start to slow down

[bwinter1946]

I agree with above recomendations concerning checking to see if the A/C compressor and condensor (Outside) fans are running.

If the compressor is not running you might check the wiring plug going to the compressor. I found a weather pak style plug near the A/C compressor that had come loose on my BMC. The plug was on the wiring harness about a foot from the compressor. It ran aft of the compressor and towards the passenger side.

Next I have a question. If all is running well: IE inside & outside fans plus the compressor did you have the A/C switch on the dash set on recirculate? When I test drove my BMC the air worked for a while and then quit. The corrective action notes on the repair from the dealer was he added 1 lbs of freon and stated to never run the air on recirculate as it short circuits the a/c airflow back into the evaporator. He said to never run the air past the Max position. I have no idea if this is true. Since I am nowhere near a tech on A/C I just run in the Max position. Perhaps some other BMC owner will correct me here and tell me I am wrong.

My opinion after this is: If all the above is fine you probably lost the freon. I am not positive but your A/C should be R-134a freon. It should have a label on the engine cross bar on the back of the engine compartment.

Good luck.

[fxdwg]

The only thing the recirculation position should do is close off the outside air door, which prevents outside air from mixing with the already cooled air of the coach. At least on mine I can watch it open and close with the change in the controls.

[slckpurdy]

Thanks guys, I will have time to work on it this weekend. I am out of town now for the rest of the week. Its funny it worked fine for a short time and then nothing. Hopefully its something simple. Will let everyone know the outcome one more time. Thanks again