dutchster
Indy
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Joined: 10/10/2006
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I have a 1995 DutchStar 454 gas P30 chassis. At highway speeds the a/c works fine until I start to pull a hill and the vacuum goes down. When the vacuum goes below about 5 inches the compressor kicks out and the blower quits until the vacuum rises to around 15 inches. I know there used to be a switch on older cars that kicked the compressor off to pass or go up a hill. I guess my question is, is there a switch(relay) pn my p30 and if where is it and how can I bypass it? Thanks, Al
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MAJESTYPOINTERS
MONROE, MI.
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Joined: 04/08/2008
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Are you saying that the blower (fan) actually shuts off or is it posible the vents just close and you can not feel the air any more? I have never seen one shut the fan off.
Older units have a vacuum operated air box assm. that will move the flaps (doors)inside the heating and a/c unit so that the air (blown by the fan) will take different paths through the air box. I.E. somtimes it will go past the heater core to the windshield (defrost mode) and some times it goes past the AC evaporator to the dash vents (ac mode).
If the blower is still running (air just sent the wrong way)you might have either a bad vacuum line or bad vacuum canister. The vacuum canister is to give a reserve of vacuum for situations such as when you acelerate or pull hills so that the doors remain in the set position. If it is bad or not getting vacuum in the first place it is posible that your doors will move when vacuum is low.
The "Kick out" for the AC compresser is normal....That is normaly handled through the ECM (electric control modual) on vehicals of your year. Their is no way I have ever heard of to by pass that. It kicks out like that to reduce the load on the engine when more power is needed at the rear wheels I.E. acelerate or climb.
Hope this helps some.
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cdzranch
Snowflake Az
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Joined: 03/28/2008
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Look for a small check valve in the vacuum circuit. It's a one way valve, they go out often.
Dan and Cindy FMCA# 402249
2002 Itaska Suncruiser 37ft (1) slide W22 Workhorse chassis; 1990 Komfort Trendsetter 25ft 454 4bbl carb
Tow VW manx bug; '07 Honda Shadow 750
Snowflake Az.
"If you don't learn something new every day, you've wasted that day!"
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tom_kat
way upstate new york/lake george area
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Joined: 02/28/2005
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the one way valve might not be working or you could add a larger vacuum can.
1985 Class A Holiday Rambler Imperial 33 +1979 Class C Holiday Rambler Statesman 1000 = 24 ft
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Flyfisherman128
Broadalbin, NY
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Joined: 08/09/2005
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Got the same problem in my 1992 P30..it's most likely the vacuum check valve..I haven't checked mine out yet. I'm pretty sure they didn't put in a compressor cut out on a 454..lack of power is not ussually an issue.
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zmotorsports
Utah
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Joined: 11/29/2007
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It sounds like it is just deverting from the dash vents to the defrosters which is the default when vacuum drops. On my old 84 P30 gasser I added a second vacuum resevoir and this pretty much eliminated the problem. Mike.
Mike & Chrystal (F315002)
2003 Monaco Dynasty/ 26' Haulmark Edge trailer
1996 Jeep Grand Cherokee toad
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dougrainer
Carrolton
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Joined: 06/11/2007
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Motorhomes on Class A chassis's do not have a compressor cutoff under load. The only compressor cutoff is the Low pressure switch and the tstat. Your problem is a vacuum problem. Either there is a leak in the system or hoses. The add on Dash air systems on RV Class A motorhomes have natural leaks in the vacuum system. You usually do not see these as the engine keeps replacing the lost vacuum UNLESS, you are under load and the engine vacuum goes to zero and the system is losing the vacuum before the engine vacuum comes back. Find the leak or add a second vacuum reservoir OR install a 12 volt vacuum pump like the Diesels have so you do not have to worry about engine vacuum supply. Doug
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itsalleasy
USA
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Joined: 07/20/2007
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I am going to disagree about the compressor cutout. My a/c cuts out under wide open throttle (or close) on my mh because of the ecm and has on every ecm controlled vehicle I have had. Because it is controlled by the the ecm there really is no way to defeat it without putting in a switch to engage the clutch. I have never seen the blower cut out.
The evaporator, condensor, etc., may be after market but the the compressor is almost always from the chassis builder.
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