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1993 Ford E350 A/C Not Cooling #4459411
07/14/17 03:22 PM
07/14/17 03:22 PM
Joined: May 2016
Posts: 293
New England
NibbanaBanana Offline OP
NibbanaBanana  Offline OP
Joined: May 2016
Posts: 293
New England
I have about 60psi of static pressure in the system. When I turn the ac on, the clutch engages but quickly cycles off at 85psi high side, 26psi low side.

I jumpered out the two pin pressure switch so that the ac clutch remains engaged. The pressures are 90psi high side and 14psi low side with the compressor operating continuously. This is the first time I have worked on ac. I would interpret this as both a bad pressure switch and low refrigerant. Does anybody have any other ideas?

The ambient temperature here is about 62F.

Thanks.

Last edited by NibbanaBanana; 07/14/17 03:23 PM.

1993 Ford E350 5.8L, 68K
2002 Ford E150 4.2L, 85K
2006 Chevy Aveo 1.6L 215K
2013 Kia Reo 1.4L, 101K
7500 OCI, M1 5-30 winter, M1 10-30 summer
Re: 1993 Ford E350 A/C Not Cooling [Re: NibbanaBanana] #4459418
07/14/17 03:31 PM
07/14/17 03:31 PM
Joined: Sep 2006
Posts: 242
Virginia, USA
Nukeman7 Offline
Nukeman7  Offline
Joined: Sep 2006
Posts: 242
Virginia, USA
The pressure switch is good and shutting off at low pressure to protect the compressor from damage. You are clearly low on Freon and need a recharge. Try adding a 12 oz. can of refrigerant (R-12 I suspect) to see if that will raise it up to maintain low side pressure in the 25 to 30 psi range when the compressor is running steady.

Last edited by Nukeman7; 07/14/17 03:34 PM.
Re: 1993 Ford E350 A/C Not Cooling [Re: Nukeman7] #4459449
07/14/17 03:57 PM
07/14/17 03:57 PM
Joined: Dec 2016
Posts: 6,259
Waco, TX
Linctex Offline
Linctex  Offline
Joined: Dec 2016
Posts: 6,259
Waco, TX
Originally Posted By: Nukeman7
Try adding a 12 oz. can of refrigerant (R-12 I suspect)


I think the 93's were R-134a?


"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."
Re: 1993 Ford E350 A/C Not Cooling [Re: NibbanaBanana] #4459454
07/14/17 04:02 PM
07/14/17 04:02 PM
Joined: Jun 2003
Posts: 17,363
Deplorable in apple valley, ca
Chris142 Online content
Chris142  Online Content
Joined: Jun 2003
Posts: 17,363
Deplorable in apple valley, ca
Whats your ambient temps? high side should be around 2x ambient temps. if its 90F high side should be around 180ish...sounds like its real cold or nearly empty.


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Re: 1993 Ford E350 A/C Not Cooling [Re: NibbanaBanana] #4459482
07/14/17 04:37 PM
07/14/17 04:37 PM
Joined: Nov 2014
Posts: 55
Florida
FSully1 Offline
FSully1  Offline
Joined: Nov 2014
Posts: 55
Florida
Search out the leak, you're under charged.

Re: 1993 Ford E350 A/C Not Cooling [Re: NibbanaBanana] #4459488
07/14/17 04:47 PM
07/14/17 04:47 PM
Joined: Sep 2015
Posts: 1,529
USA
mk378 Online content
mk378  Online Content
Joined: Sep 2015
Posts: 1,529
USA
"Nearly empty" is a much better description of this situation than "undercharged". If it has worked properly recently, it has sprung a rather large leak.

The rapid cycling is normal when nearly empty. Do not jump the switch. It will start to cycle normally once charged.

Re: 1993 Ford E350 A/C Not Cooling [Re: NibbanaBanana] #4459519
07/14/17 05:38 PM
07/14/17 05:38 PM
Joined: May 2016
Posts: 293
New England
NibbanaBanana Offline OP
NibbanaBanana  Offline OP
Joined: May 2016
Posts: 293
New England
The ambient temp is 62F. It has been converted to 134a according to a sticker under the hood but was originally R12.

I put very few miles on the vehicle and rarely ever use the ac. Maybe once every year or two. (I know that I should use it more.) The vehicle is 24 years old so I'm not sure if it's leaking fast or if it has just slowly leaked over time. I bought it 7 years ago and I'm not sure the ac worked all that well when I got it but I had other things to worry about. It is a 14 passenger bus that I built into a camper. We had a very hot spell last summer and now the wife wants the ac working for our vacation this year.

I already added 1 large can of refrigerant before I got my manifold gauges to try to diagnose the problem. It has a rear unit so takes a lot of refrigerant.

So, the pressure switch turns the compressor off when the pressure is too low. Does it also do the same when the pressure is too high?

Thanks.


1993 Ford E350 5.8L, 68K
2002 Ford E150 4.2L, 85K
2006 Chevy Aveo 1.6L 215K
2013 Kia Reo 1.4L, 101K
7500 OCI, M1 5-30 winter, M1 10-30 summer
Re: 1993 Ford E350 A/C Not Cooling [Re: NibbanaBanana] #4459525
07/14/17 05:49 PM
07/14/17 05:49 PM
Joined: Oct 2004
Posts: 7,984
Cincinnati, OH, USA
bullwinkle Offline
bullwinkle  Offline
Joined: Oct 2004
Posts: 7,984
Cincinnati, OH, USA
Originally Posted By: NibbanaBanana
The ambient temp is 62F. It has been converted to 134a according to a sticker under the hood but was originally R12.

I put very few miles on the vehicle and rarely ever use the ac. Maybe once every year or two. (I know that I should use it more.) The vehicle is 24 years old so I'm not sure if it's leaking fast or if it has just slowly leaked over time. I bought it 7 years ago and I'm not sure the ac worked all that well when I got it but I had other things to worry about. It is a 14 passenger bus that I built into a camper. We had a very hot spell last summer and now the wife wants the ac working for our vacation this year.

I already added 1 large can of refrigerant before I got my manifold gauges to try to diagnose the problem. It has a rear unit so takes a lot of refrigerant.

So, the pressure switch turns the compressor off when the pressure is too low. Does it also do the same when the pressure is too high?

Thanks.
No, it is only a low side switch, which opens on pressure drop. If your gauges have a temperature scale, a decent starting point is the pressure which corresponds with 45F, as the system gets colder it will drop. In my experience the R134A adapter fittings are a common place for leaks.


06 Ram 3500 CTD 4X4(FG Venturi), 93 GMC C3500 6.2, 89 F-450 7.3, 98 XJ 4.0(XG8A), 05 xB(XG3600), 18 Transit 3.7, 03 Merc Grand Marquis 4.6 2V(XG2)
Re: 1993 Ford E350 A/C Not Cooling [Re: NibbanaBanana] #4459539
07/14/17 06:05 PM
07/14/17 06:05 PM
Joined: Sep 2015
Posts: 1,529
USA
mk378 Online content
mk378  Online Content
Joined: Sep 2015
Posts: 1,529
USA
Yes especially if you have a tall aluminum adapter fitting on the low side. Those are junk. NAPA may still sell the yellow steel ones that are much better.

Re: 1993 Ford E350 A/C Not Cooling [Re: NibbanaBanana] #4459674
07/14/17 09:09 PM
07/14/17 09:09 PM
Joined: Jun 2003
Posts: 17,363
Deplorable in apple valley, ca
Chris142 Online content
Chris142  Online Content
Joined: Jun 2003
Posts: 17,363
Deplorable in apple valley, ca
Originally Posted By: NibbanaBanana


So, the pressure switch turns the compressor off when the pressure is too low. Does it also do the same when the pressure is too high?

no. Most r12 systems did not use a high pressure cut out switch. If the shop did the conversion correctly they should have added one.


02 Wrangler durablend 10w40
87 F250 traveler 15w40
04 Tahoe super-s 10w30
Z400 castrol T 10w40
Can am maveric edge 5w40
57 case tractor 15w40

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