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cretan
30-06-2007, 04:14 AM
my trucks a\c blows marm air at idle.when rpm's are up works fine.At idle I checked the low side .with the clutch engaged pressure is around 60.When the clutch dis-engages the pressure quickly climbes and bottoms out my gauge.Is the pressure rise normal or is there a problem with the system?Thanks!!!!!

bruisermac
23-07-2007, 10:54 PM
whats the head pressure like??

Brian_UK
23-07-2007, 11:08 PM
Sounds normal, system pressure equalizes when the compressor stops.

2002kahuna
24-07-2007, 04:45 AM
What refrigerant is in your system?
Normal suction pressure on R134a system while running should be 35 to 45 PSI tops. R-12 or most of it's replacements run around 35 PSI tops.
Over those pressure I would look for overcharge, weak compressor, or non condensables.
What is your head pressure while clutch is engaged and system running?

mohamed khamis
24-07-2007, 05:33 AM
Hi all

It is very normal, when the clutch is engaged to the engine this means the system compressor on working and there is a pressure difference creation between the LP and Hp sides. However, when the clutch is de-engaged the compressor is stopped and the evaporating pressure is increased and the head pressure is decreased until stabilization has been achieved.And the blowers only are working to circulate the air around the commuters until the thermostat sense the cut in temperature to energize the clutch again to re-engage and the system starts its work. I wish it is clear

Cheers:)

rjohn
11-08-2007, 04:57 AM
In short-compressor pumps , suction -discharge line,
cool- hot
temp by feeling temp. fan blows air through condenser.
liquid exits condenser cooled down. orifice or exp valve
restricts liquid flow to a Cool feeling evaporator inlet. Evap outlet aka suction should be cool .
in vechicle air from duct cool.
If not check useing experienced person the ***** level-pressures. low with engine above idle 10-40 psi.
high discharge 250psi . or lower ,Cool condenser reads lower hot ones higher. fill slowly if needed. 2, 12 OZ cans from totally empty should have cool ac do not exceed max charge . R12 to 134A conversion is usually less *****.
Now wasn't that common sense.

rjohn
11-08-2007, 04:58 AM
Automotive Air Conditioning: Quick test and repair.
fast service ac shop "$19.95 ac check,experience." should I mention years.
To new help I would best say , Common sense.Look around touch and listen. Noisy parts,Clacking compressors,squealing belts or fans? repair first. Poor air flow,condenser or evap, good air from ducts Can you set inside control with correct response , heat to floor. ac to duct,recirc door (more fan noise-Air fron floor).defrost to windshield ect.
Automotive ac can be tested by observation no special tools needed.Looking for good performance from several areas is most of the clues you will need Engine speed must be above idle 1200 rpm or somewhat more 1500 .. Does compressor turn on ,is there airflow at front of condenser, radiator area.Touch breifly the compressor lines , suction and discharge with a running vehicle,ac on . Suction should be cool , discharge hot but not scalding. is air warm leaving the condenser if discharge @ compressor is hot? spray water on condenser to cool it
if you suspect poor fan clutch , belt driven . ele fan running can be obstructed by leaves ect between condenser and radiator .air flow must be strong. think box fan on high.
If all seems good ie;compressor pumps and has warm discharge, condenser cools ,exit from condenser is near outside temp or somewhat warmer. follow the condenser liqid line along tward the passenger compartment touching it in several places , newer vehicles have orifice ,other including older have exp. valve.did you find a temp change? Many have orifice in line (ford) or in fitting Chevy ect.Foreign prefer exp valve (older).
There should be a temp change @ orifice or exp valve cold is good result. Frosted up may be low refrigerant level. Fast cycling from compressor may be low ***** also.
In short-compressor pumps , suction -discharge line,
cool- hot
temp by feeling temp. fan blows air through condenser.
liquid exits condenser cooled down. orifice or exp valve
restricts liquid flow to a Cool feeling evaporator inlet. Evap outlet aka suction should be cool .
in vechicle air from duct cool.
If not check useing experienced person the ***** level-pressures. low with engine above idle 10-40 psi.
high discharge 250psi . or lower ,Cool condenser reads lower hot ones higher. fill slowly if needed. 2, 12 OZ cans from totally empty should have cool ac do not exceed max charge . PS R12 to 134A conversion is usually less *****.
Now wasn't that common sense.