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Old 05-17-2018, 12:59 PM   #1
Mini-Skoolie
 
Join Date: Dec 2015
Location: SE WI
Posts: 32
Year: 2001
Coachwork: Eldorado
Chassis: Ford E450
Engine: 7.3
Having trouble with E450 A/C system. HELP needed.

Are there any automotive A/C gurus out there? I just assembled the main A/C on my 2001 E450 shuttle and it's not functioning properly with a recharge.

I had removed the aux/rear a/c blower/evap/condenser/fans/hoses. It had been Tee'd into the front hoses with special aluminum tubes. I Didn't flush the front evap, compressor or hoses. I installed a new front condenser, accumulator, orifice tube, low pressure switch. Vacuumed system(held vac for 30 minutes), added oil, added approx 44oz 134A. Compressor clutch kicks on at 44ps and spins for 10-15 seconds. Low pressure drops very quickly from 44psi to 25psi. Compressor shuts off. Low side pressure rises VERY slowly (2-4 minutes) back to 44. Then repeats. High side goes up from 150 to 200 ps when compressor runs. It is 80 deg out. No cold or sweating A/C hoses. No cool or cold interior air. A/C sticker underhood says that system without rear a/c holds 2lbs, 12oz. That's what I was trying for.

Any ideas for me. Thanks.
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Old 05-17-2018, 01:03 PM   #2
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 9,689
Year: 1991
Coachwork: Carpenter
Chassis: International S3800
Engine: DT360
Rated Cap: 7 Row Handicap
sounds like your orifice tube clogged right up dfrom leftover dirt in the system or the components you sourced.. id reclaim it, pull the orifice and check it.
-Christopher
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Old 05-17-2018, 02:32 PM   #3
Mini-Skoolie
 
Join Date: Dec 2015
Location: SE WI
Posts: 32
Year: 2001
Coachwork: Eldorado
Chassis: Ford E450
Engine: 7.3
It looks pretty clean to me. It was installed with the shorter end into the line going into the evaporator. It appears clean enough to reinstall. I just disconnected both lines at the evaporator and blew it out a bit with compressed air. Lots of oil in there.

Steve.
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Old 05-17-2018, 02:37 PM   #4
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 9,689
Year: 1991
Coachwork: Carpenter
Chassis: International S3800
Engine: DT360
Rated Cap: 7 Row Handicap
how much oil did you put in the system? you probably only need 8 oz of oil total in just the dash air.. and did the original system have a TxV in it somewhere that got missed and so you are trying to operate with 2 metering devices?
-Christopher
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Old 05-17-2018, 02:49 PM   #5
Mini-Skoolie
 
Join Date: Dec 2015
Location: SE WI
Posts: 32
Year: 2001
Coachwork: Eldorado
Chassis: Ford E450
Engine: 7.3
I added 5-6 oz oil when I reassembled. Poured a few in the condenser, a couple in accumulator, and added 1 when charging. I used PAG46. I don't believe this system has/had expansion valve. I removed what appeared to be an original orifice tube from the evap inlet tube when I had the hoses disassembled to remove the rear system.

Steve
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Old 05-17-2018, 03:19 PM   #6
Mini-Skoolie
 
Join Date: Dec 2015
Location: SE WI
Posts: 32
Year: 2001
Coachwork: Eldorado
Chassis: Ford E450
Engine: 7.3
Some more information. Yesterday after I had charged the system I left the engine run/idle for an hour or so. The high side pressure kept creeping higher and higher. It made it up to the 325-350ps range. Low side stayed between 20 and 50 or so.
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Old 05-17-2018, 05:35 PM   #7
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 9,689
Year: 1991
Coachwork: Carpenter
Chassis: International S3800
Engine: DT360
Rated Cap: 7 Row Handicap
is the condensor or the liquid line from it getting hot? this seems like no heat being moved from the condensor or a grossly over-charged system.. a blocked orifice usually wont make the head pressure go up like that.. in fact the head pressure will go low if you had a blockage.. something just seems off here..
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Old 05-17-2018, 07:24 PM   #8
Mini-Skoolie
 
Join Date: Dec 2015
Location: SE WI
Posts: 32
Year: 2001
Coachwork: Eldorado
Chassis: Ford E450
Engine: 7.3
I just started over with vacuuming the system. Then I turned on A/C and bypassed the low pressure switch to get the compressor spinning. I charged with (1) 12oz can. While charging, the can, sight glass, low side manifold and hose began to freeze up. The low side pressure increased to about 10, then dropped into the vacuum side. High side pressure is at 60.

I'm not sure how to best test for a blockage within the components besides taking it all apart and blowing through everything. Also, how can I determine if there's an internal compressor problem?

Thanks for the help.
Steve
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Old 05-17-2018, 08:35 PM   #9
Mini-Skoolie
 
Join Date: Dec 2015
Location: SE WI
Posts: 32
Year: 2001
Coachwork: Eldorado
Chassis: Ford E450
Engine: 7.3
I just found a post with a similar situation as mine.

http://http://www.autoacforum.com/messageview.cfm?catid=2&threadid=14482
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Old 05-18-2018, 06:13 AM   #10
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 9,689
Year: 1991
Coachwork: Carpenter
Chassis: International S3800
Engine: DT360
Rated Cap: 7 Row Handicap
the site glass started to freeze? where is the site glass in the system? it should be after the condensor and before the orifice tube..

freezing after the orifice tube and before the evaporator is normal and expected on a low-charged system..
-Christopher
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