94 Monaco Executive 40' DP Dash Air issue

[Ronbstewart]

I've owned this coach for almost 2 years, I noticed recently dash air was no longer blowing cold. Check the compressor and it wasn't operating. To test I connected a direct jump wire, it engaged and remained engaged when I disconnected the jumper and air started to cool. I turned it off, but it failed to engage again when I turned it on again. Contacted a certified AC tech I know who works on cars and trucks, he suggested it needed freon (still has R12 system) ordered a 12 ounce can on line and he installed it using a simple little hook-up that just taps the can (no gages) had to use jumper to engage clutch again, put in 12 ounces, it cooled some,but wouldn't engage again after being shut down. He suggested I order 1 or 2 more cans, he will install it using gages. Low press port is located in hose several inches from compressor, but no luck locating high press port yet if there is one, also press switch at front of coach has current thru it, not sure why clutch is not engaging. Compressor is on engine in the rear, hoses up front seem to get quite hot to me after it has been operating for about 5 min. I'm also wondering if I should have the system upgraded to R134, anyone experienced this problem or know where the high press port is?

[Mike Canter]

Ron, I use this Freeze 12 in one of my older BMWs. It works great and is a lot cheaper that R-12. It is about the same price as R-134 but you don't have to convert anything. You can buy it at some auto parts stores or order it directly or do a search on the web. According to Federal Law you have to have a license to buy R-12.

freeze 12 r12,FREEZE12 COMPATIBLE R12 REPLACEMENT A/C REFRIGERANT

You only need the high pressure port to troubleshoot using gages.

[mahon1993]

There is usually a pressure switch on one of the coolant lines that will not allow the compressor to turn on if the coolant pressure is low. I think you need a different AC guy. You need someone with the right equiptment to test the system.
Greg

[Ronbstewart]

Thanks Mike and Mahon for the replies. I wasn't aware of the product "Freeze 12", R12 runs on average of about $40 per 12 ounce can with shipping. The Tech I had install the can I purchased has the proper tools as he has his own shop and services about 3 or 4 AC systems a day although he doesn't normally do coaches. we though the jiffy kit would be a quick fix. I do most of my own light work such as oil changes, filters changes and electrical work. I understand my AC electrical system, but don't know all the component locations and wire routing. For instance the AC pressure switch is located up front in the Gen compartment, there is current flow threw it, but I'm not sure if the current goes directly back to the compressor located in the rear on the engine or thru other components and relays before getting there. Also I didn't think to test the pressure switch before the freon. Tech claims the R12 systems have a press release valve the won't allow the system to be over pressured as can be done in R134 system.

[Mike Canter]

If you take the plug off the pressure switch and jump the two pins in the plug with a paper clip the compressor should turn on regardless on how much freon is in the system. If does turn on then it is most likely just low on freon. These systems are not sealed like a house unit and will slowly leak down over long periods of time. The reason I like to use Freeze 12 is everytime I have converted a car from R12 to R134 the compressor has failed in the near future. (before you all jump here let me tell you I do know what I am doing)The replacement compressors for an R12 system are now modified to accept R134 also so they will work without failing. I have not had a compressor fail after converting to Freeze 12. You don't have to change oil or orings. My wife's older BMW that uses Freeze 12 will freeze you out of the car. If you decide to use Freeze 12 then read the instructions on the website carefully because if I remember correctly you only put in 80% of the Freeze 12 than was originally called for with R12. I normally fill a AC system with close to the amount of freon specified then I use a Infared temp gun and check the temps of the lines going in and out of the dash evaparator. When the input and output line temps are both the same then the system is optimized,

[Ronbstewart]

There is current flow completely thru the press switch, but for some reason its not getting back to the compressor clutch. From this point should my first check be having a tech put gages on the AC to check system pressure or check for the location loss of 12V power somewhere between the pressure switch and the compressor clutch? Thanks so much for the help you have given.

[Ronbstewart]

Follow up: ordered several cans of Freeze 12, had tech install them with use of pressure pressure gages, both high and low pressures are in limits. 12V flowing through low pressure switch but not getting back to compressor clutch, AC seems to cool when compressor is jumped to 12V. Are there any components located between low press SW and compressor? When the wire is disconnected from both items and tested with a test light connected to 12V the test lite will come on indicating the wire is grounded or there's a relay or something in between. Any one out there have knowledge of the wiring for this system?

[Ronbstewart]

Had a happy ending to my problem someone suggested I call Monaco, I thought it would be a long drawn out customer no service deal for a coach as old a mine. Took about 3 minutes to get through, 3 minutes get hold of someone with knowledge about the AC wiring. Told me he didn't have a 94 wiring diagram, but had a 95 as the Executives had same wiring for several years and faxed it to me in another 3 minutes. Really great service from Monaco. Turns out there are 7 small relays all the same size and each has 1 mounting screw mounted vertically on drivers side of forward bulk head in engine compartment, easy access by raising the bed. Starting at the top counting down #3 controls compressor clutch and #4 controls condenser cooling fan located almost over muffler on passenger side. #3's control power come from the low press SW and #4's control power comers from #3. Both had wires not making good contast as a result of all the dust and soot that ends up in engine compartment. Cleaned those and dash air is now working great. Thanks for all the info, comments and suggestions.

[Madrona]

Quote:

Originally Posted by Ronbstewart Had a happy ending to my problem someone suggested I call Monaco, I thought it would be a long drawn out customer no service deal for a coach as old a mine. Took about 3 minutes to get through, 3 minutes get hold of someone with knowledge about the AC wiring. Told me he didn't have a 94 wiring diagram, but had a 95 as the Executives had same wiring for several years and faxed it to me in another 3 minutes. Really great service from Monaco. Turns out there are 7 small relays all the same size and each has 1 mounting screw mounted vertically on drivers side of forward bulk head in engine compartment, easy access by raising the bed. Starting at the top counting down #3 controls compressor clutch and #4 controls condenser cooling fan located almost over muffler on passenger side. #3's control power come from the low press SW and #4's control power comers from #3. Both had wires not making good contast as a result of all the dust and soot that ends up in engine compartment. Cleaned those and dash air is now working great. Thanks for all the info, comments and suggestions.

Thanks for getting back to us and especially for your happy outcome! I wish everyone that realizes a solution would post it to help us all. Even with an entirely different coach, the cause and solution you found should help everyone when something doesn't work. Great Job!