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Dash Air electrical

I have reached the end of my expertise on dash air.
The compressor will not run.
I have traced the power as far as I can.
I have power at the switch in the dash.
I have power at the relay mounted on the isolator board.
NORMALLY, I can jump the wires in the three way switch at the condenser to force the compressor to run but this time it won't work.
I am going to sit and think about it for a while and if anyone has any insight I would appreciate it.
Gary B

Re: Dash Air electrical

Reply #1 –
I think I would start at the compressor.  Turn the system on and see if you have voltage at the compressor clutch.  Seems like mine only has one wire. 
Bill and Doris
93 GV gas

Re: Dash Air electrical

Reply #2 –
Have you tried jumping across the relay contacts on the isolator board, not sure of the  wiring on your model, but the relay that you say you have power to, the question would be; is the contacts conducting power to the load side/compressor?
I just had a condenser fan problem, found the fan motor was dead, so FT sent me a new exact replacement, bingo all good, but I got a real good picture of how the a/c system works and THAT relay has to conduct to the compressor clutch/pressure switch line.
FWIW

Re: Dash Air electrical

Reply #3 –
OK, After more study I jumped wires from terminals  87 and 30 at relay.  That made  the compressor run. I replaced relay with what I think is a good one but still no go.  I'm off to find a Bosch relay could be the one I think is good really isn't.
On condenser fans, I can get them to run by jumping terminals at switch at condenser.
Thanks for all suggestions, I am determined to solve this.
Gary B

Re: Dash Air electrical

Reply #4 –
Gary, those relays are available everywhere, I have gotten them from a Ford dealer parts, most any auto parts house should have them, the problem is, there are many different quality made, like Advance, Auto Zone etc are real cheap and do not seem to have much of a life, If you can find the Bosch relays, you are way ahead of the game.
Also make sure the wire terminals are clean and snug, for some reason some of these either were never tightened correctly or they work loose, I had a problem with loose 12+ supplying power to the two relays when I first took delivery of my coach, I was so over whelmed with all the "new" and I took delivery in Jan, that I never noticed the A/C was not working, the fan just blew air, Haw nother education.
FWIW

Re: Dash Air electrical

Reply #5 –
Well, Relay not the problem.  New one no help.
I jumped two terminals at the relay on the isolator board, that runs compressor, then checked charge, it was low as usual. Condenser fans operate all right....  SO

By doing this I will have AC but still have not solved the problem.
Gary B

Re: Dash Air electrical

Reply #6 –
Have you checked the refrigerant pressure?  If the refrigerant has leaked out the pressure will be low.  There is a low pressure switch that detects that and prevents the compressor clutch from engaging thereby saving your compressor from mechanical failure.
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: Dash Air electrical

Reply #7 –
In deed, do not run it low on the freon, if it is the R134 stuff, my unit needs 45 psi on low and 250 psi on high side I think the numbers were for it to operate correctly.  Running by jumping out the pressure switch is asking, no, begging for  more trouble.
FWIW

Re: Dash Air electrical

Reply #8 –
Good point about Bosch aftermarket relays. A lot of auto parts stores sell clones and ebay has knockoffs for $3 or so. The real deal is only around $10 so with our Foretravels using so many of them, good to have a couple of extras.

Here is a great page with over one hundred schematics and examples. http://www.google.com/search?q=Bosch+relay+wiring+diagram&hl=en&prmd=ivns&tbm=isch&tbo=u&source=univ&sa=X&ei=4cFrTu2PE6nTiAKv5eGgDg&ved=0CBoQsAQ&biw=1355&bih=632  Gives examples of how to wire driving lights, horns, you name it.

Example of a real one (30 amp) at: New Bosch Relay 0332019150 12V/ 30A | eBay

They come in several styles but our application usually has the little ear sticking up with a hole in it for mounting.
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Dash Air electrical

Reply #9 –
Quote from: Dave M –
In deed, do not run it low on the freon, if it is the R134 stuff, my unit needs 45 psi on low and 250 psi on high side I think the numbers were for it to operate correctly.  Running by jumping out the pressure switch is asking, no, begging for  more trouble.
FWIW

Agree with Dave. I was smart, jumped the pressure switch on a BMW, compressor came on and about 10 seconds later a high pressure hose blew spraying 134 everywhere. Had been bent over looking at all the hoses a few seconds earlier. Not the stuff you want to get in an eye.
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Dash Air electrical

Reply #10 –
I know that the high pressure switch is working, when set point is reached condenser fans kick in.  Low pressure not a problem.  Problem began as no run of compressor. 
Wiring diagrams are not adequate, it shows the relay on the isolator board but then other than a note that says to AC COMPRESSOR and TO CONDENSER Fans  there is no indication that I can find of what is controlled by other terminals on relay.
Thanks for the ideas, I am still open to a solution.
Gary B

Re: Dash Air electrical

Reply #11 –
Jerry and Dave, this Frigiking has no separate low/high pressure switches.  They are combined in what I have heard called a TRI Switch.  The switch is located in the front of the coach at the condenser, four wire switch. Since this is a GV the R134 service ports are also in the front near the condenser.
Gary B

Re: Dash Air electrical

Reply #12 –
Is it possible that there is a low temp switch (freeze detect) on the evaporator that is faulty?
Dave and Nancy
1999/2013 U270 36' Xtreme
Motorcade # 16774
2013 Subaru Outback
KD0NIM

Re: Dash Air electrical

Reply #13 –
Dave, Now that you mention it I have not verified that the Freezstat is operating, just overlooked it... Thanks, I'll look at it later t'day.
This is why this forum is so useful, it reminds me every once in a while to get my head out of my a..  :)
Gary B

Re: Dash Air electrical

Reply #14 –
Gary, I have a 2003 320 (designer) but I am sure the systems are similar.  As far as the relay wiring, terminal #30 is the line, terminal #87 is the load.  #85 and #86 are a simple ground and a trigger from the dash switch, #87A is not used.  All sensors are just wired in series through the trigger wire, ultimately to end up at this relay.  If your coach has a evaporator freeze switch, it should be a small square box with a terminal sensing tube that is stuffed into the evaporator core.  It is very possible you just have a bad ground wire at the relay, or it is not getting a signal from the dash switch.  I had trouble with the dash air in my coach and I am very familiar with the operation of this system.  If you would like to call me, I will do everything possible to help you.
Call me at any time

Gregory S
(708) 715 5517
2003 Designer

Re: Dash Air electrical

Reply #15 –
Greg, I'll grant you the honor of nominating me for the DUMBASS award of the week ( month, year, decade ).  The ground wire at the terminal connection for the relay was broken and I know exactly how and when it got broken.  It was fastened to the back of the metal mounting plate on which the isolator is mounted.  When I put new batteries in last week We must have snagged the ground wire while wrestling these 160 pound beauties into the compartment.  Result no ground and answer to the problem.  Thanks for pointing me in that direction.
I owe you the beverage of your choice when we meet up somewhere. ^.^d
Gary B

Re: Dash Air electrical

Reply #16 –
Gary, I am glad I was able to help.  As far as my choice of refreshments, just you are ready, should the moment arise, I enjoy a tall glass of filled with ice, a healthy splash of Early Times Bourbon, and A & W Root Beer.  May sound strange, but try it!

Gregory S
2003 Designer 








Re: Dash Air electrical

Reply #17 –
Greg, I am misinformed.... I thought that A & W Root beer only came with ice cream.  I'll have to research further.  :)