orleanzmax

iTrader: (8)

97 gle with the auto climate. i have overhaul the complete unit. i have new fan assembly, condenser, expansion valve, drier, comperssor, evaporator. new hoses as well. the system worked fine for that week until today. the problem i have, is that when i turn the ac on the system does not engage. the clutch on the compressor does not come on nor the fans as they should. i try to jumping them direct the system turns on. so i got new relays. still doesnt engage. when i jumped them direct, it engage but however the ac does not blow cold. so i check line pressure and it shows correct pressure reading so i guess the freon is circulating. but the low side line does not get cold even though it has the correct psi so i know its not circulating correctly. has anyone had a similar problem or any ideas i should check. i will put a new pressure switch on but i did jump it off there as well and the system engage but does not blow cold just as before when i jumped it from the compressor. any help would be greatful

alset2

iTrader: (1)

do you have a full set of gauges or just the low side one???
well either way you can put it on high blow and rev the engine up to 2500~3000 rpms and see if the low side pulls down into a vacume,this would indicate a stuck open expansion valve which would explain the no cooling problem,as far as the electrical from what I read it seems you found the problem at the low pressure switch correct?

SVI30

You can open just the bottom of the evaporator box without disassembling the whole airbox. With the A/C on max, see if the pipes inside are frozen. If it is frozen, then the expansion valve is stuck open.

The thermal side has very few controls, the clutch is controlled by the ECU and the triple pressure switch is monitored by the ECU. The cabin A/C control box doesn't control the thermal side directly.

As alset2 said, check pressure on high side and low side.

orleanzmax

iTrader: (8)

i do have full set of guage but at that time i didn't have it to use. the pressure is maintain through out the rev range on the low side at 30 fluc. only maybe 2 psi when off throttle but gets stable quickly. i tested as you have mention. i was questionin the main electrical ecu in the center console. cuz i checked the pressure switch and it has 2 hot and 2 ground when ac off. when ac turn on. it has 3 hot and 1 ground. my other max which is working fine had the opposite. 3 ground and 1 hot. but same when off. the evap and ac hose or lines does not get cold at all. i'm questionin why my system can not get turned on.

SVI30

What is the pressure on the high side?

There are two switches in the triple pressure switch. When the A/C is on, one normally open switch closes and short the fan relays to GND to turn the fans on (connector E25, terminals 3, 2).

The other switch (connector E25, terminals 1, 4) is normally on but when the pressure is too high, it opens to tell the ECU to dis-engage the compressor clutch.

On connector E25, terminals 1, 2 are close to the clip and terminals 3, 4 are away from the clip. Terminals 1 and 4 are diagonal on the switch connector and terminals 2 and 3 are diagonal. So check the switch with the car off and see if you get continuity in terminal 1, 4 and open circuit in terminal 2, 3.

Terminal 4 is pulled to 12V when the car is on and A/C switch is on. In turn terminal 1 is pulled to 12V and it tells ECU to engage the compressor clutch. When the freon pressure it too high, this switch opens and the ECU dis-engages the compressor clutch.

The other switch for fan relay is GND on terminal 2 and pulled-up (12V or 5V) on terminal 3 when the car is off.