Engine Size: 3.8L
Refrigerant Type: 134a
Ambient Temp: 90
Pressure Low: 35
Pressure High: 225
Country of Origin: United States
I replaced the Condenser on this car after locating a leak. The AC Lines also were replaced due to the Schrader Valve in the High Side fitting being stuck open and I could
not remove it. Lastly the Accumulator/Dryer was replaced as per the TSB from GM which states they should be if older than 5 years cause of the Desiccant aging.
System was vacuumed down to 28 Hg several times and held.
The GM FSM I have uses a Liquid Low Side Charge method so I did 4 12 oz cans of 134a for 48 oz that way. The R12 Charge listed on the R4 Compressor
is 3.25 lbs (about 52 oz). Pressure Cycling Switch was adjusted down to 21 PSI from the factory 25 PSI.
At this point everything seems to be working as it should best I can tell. Clutch engages and disengages at the right pressures. It is a bit noisy though.
In park at idle once the engine is warmed up and the clutch is engaged I'm only getting about 69 degrees F at the center vents with the ambient air temp 80 to 90 F.
Gauges show 35 PSI Low Side and 225 High Side. Evaporator Inlet and Outlet pipes are "sweating" and about the same temp to touch.
I've driven the car around for about 20 min's and it doesn't get much colder. The FSM says I should be getting 34 degrees F (albeit w/R12) so I'm wondering
how can I be so far off w/134a.
Now in my daily driver (2005 Audi A4 w/dual climate control) I never set it below 73~75 degrees and the same for the programmable thermostat for the Central Air
at home so I'm not complaining. Just wondering if I can do something more or worse did something wrong.
Sorry for the long first post
Thanks for Reading
How much oil is now in the system? What are the pressure readings at 1500rpm?
I measured 2oz when changing the Accumulator/Drier so I added 4 oz (FSM says to add 2 oz over the amount measured when drained)
I added 1oz into the new Condenser when I installed it. That amount again was from the FSM.
Nothing was added to either the Compressor or Evaporator since they weren't replaced.
Total amount of oil in the system according the the Sticker is 6 oz.
Forgot to mention that I did replace the O-Tube. The old one when removed did have some black dirt on it but not excessively so.
The formula I used for charging was taken from a GM TSB. (amt of R12 Charge x .9) - .25 = R134a Charge
Yesterday I went out again and checked the system with the gauges and readjusted the Pressure Cycling Switch to 21~22 PSI. Seems it was at 18~19 PSI before.
Outside Ambient Air Temp: 80 Degrees F
Engine: Warmed up and at idle
Blower on High and Temperature Selection was Normal.
Gauge Reading Low/High: 30 PSI/200~205 PSI
Left Center Vent Temperature Reading: 65 Degrees F.
I'll check the System at 1500 RPM's later after work and report back although air temps today will be between 65 and 68 degrees F
Thanks for replying
Edited: Mon August 25, 2008 at 11:03 AM by MOrbid
Okay I tried to get the gauge reading while the Engine RPM's were at 1500 after the car warmed up.
Outside Ambient Air Temp:75 Degrees F
AC Fan Selector: High
AC Temp Selector: Max
Trying to hold the rpm's at 1500 was hard so it's 1475 to 1600 according to my OTC Monitor.
In any case the Center Vent Temp was 46 but the compressor kept cycling. Not continously but
off and on at the designated points set at the Pressure Cycling Switch. About every 15 ~ 20 seconds I wanna say.
So the gauges never settled in one spot like before when the Clutch was engaged all the time at idle.
The low side does sorta pause at around 22~23 psi before dropping down to 21 and the Clutch kicks in.
I was out there for a good 30 minutes before I gave up due to the car being low on petrol.
Edited: Mon August 25, 2008 at 5:27 PM by MOrbid
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