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Topic: Dash AC question (Read 726 times) previous topic - next topic

Dash AC question

Had an Ac Technician come over to inspect my AC and he told me that I had a plugin connection missing on the low side (blue) and that it was there to protect the compressor I've check all around the engine compartment followed the Ac lines and  wires can not find this male connector to plug in to this female connection I think it's To measure the pressure on the  low side for the computer? The air condition was work till  now. The Electric fan let's go and the condenser fins are all rotted out so I had him come in to check Freon levels and to see if it was worthwhile repairing he told me everything seem to be all right but he mentioned this connection Freon levels and compressor  and expansion valve where OK just needs a new condenser assembly.can anyone check there AC lines if this plug exist on there line this coach is 21 years old I'm thinking the computer doesn't look at the air condition. the coach is older than he is this young tech is working  in the new age and maybe this old coach is before his time nice young man he knows more than I do just puzzled over connection.everything was working
Rick & Hilda looking forward to full- timing one day for now couple of months at a time
1999 U270 3602
Built number  5530.  Feb 1999            Motorcade  number 18438
8.3 Cummins Allison six speed with brake  retarder
Purchased Nov 28 2019

Re: Dash AC question

Reply #1 –
So yes generally there is two switches one low pressure and one hi. Mine has three? Two on compressor and one on the dryer. I do know the dryer is normally open with no pressure if that helps. There is no computer controlling it. Real analog to my knowledge. Haven't looked into the book yet. I do know I'm unable to get the low side to come up high enough without overcharging the high side. Currently expecting between 15-20 psi on low side. Mine prior was -20 do to expansion valve and or dryer being plugged. Don't know which helped but I will say the expansion valve was black colored inside? I blew threw the dryer and it to seemed restricted. I charged using a thermometer in the front vent and once lowest temp was found verified hi pressure was not too hi and low was not too low.
Scott

Re: Dash AC question

Reply #2 –
Look at the hardware in the dash and see if it has a sticker or information about the manufacturer.  The dash AC in my 2003 U320 was built by SGM Company.  I contacted them and they were very helpful, including providing a wiring diagram for the system.

Keith
2003 U320 38' #6197

Re: Dash AC question

Reply #3 –
So for a 2001 270/295/320 they are a simple analog system third switch is binary switch on dryer and it is in series with hi pressure switch
Scott

Re: Dash AC question

Reply #4 –
On my system the high pressure switch was bypassed. I also have one on my dryer.
If they are all hooked up I believe the are wired in series so if one goes out the compressor
won't run. It they are safeties so the compressor won't run if there is not enough pressure.
I don't think they go through any computer. I also think only one is necessary, my Monaco
only had one.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Dash AC question

Reply #5 –
Our coach has a two normally open pressure switches. Single dash wire that calls for cooling, sends 12v to belt driven engine A/C compressor.

This wire is connected to one pressure switch, then out of switch to other pressure switch, than out of switch to compressor.  One switch is on low side hose and other on high side hose.

For 12v to reach from dash to compressor magnetic clutch, both pressure switches must be closed.

Low pressure switch opens when pressure drops below some pressure setting, probably around 4 PSI. High pressure switch opens when pressure is too high, maybe over 100 psi. I am not sure of pressure settings, but these are a simple wiring diagram.

When system is empty, I temporarily manually jumper low switch to get compressor running to refill system, until there is enough pressure to keep low switch closed.

Other coaches are wired different and there are High/Low combo switches.

Compressor protection is achieved by turning off compressor when refrigerant leaks out, dropping pressure below low pressure switch setting.

Re: Dash AC question

Reply #6 –
I have had Foretravel, MOT, Bern'd, and my local semi shop all work on my A/C. With the end result being over $3000 spent and still no dash A/C. I run the generator and both roof A/C. Everything has been replaced. After reading several posts, I believe the problem is a plugged valve going into the duck work under the dash. Everything at the rear of the coach has been replaced. Someday I will go after it as it is well hide but one of our members did a excellent job writing up a fix.
John
1998 U270 34'

Re: Dash AC question

Reply #7 –
The only value at the dash is the expansion valve at the evaporator and if they were to hock up to the Gage set on the line in the back high and low red and blue it should tell you if the expansion valve is working the valve is not very expensive  it's probably a days work to get at it to replace it. The young guy that check my AC this morning said mine was OK by the Gadges
Rick & Hilda looking forward to full- timing one day for now couple of months at a time
1999 U270 3602
Built number  5530.  Feb 1999            Motorcade  number 18438
8.3 Cummins Allison six speed with brake  retarder
Purchased Nov 28 2019