1st a/c thread of the year! 98v70
 

here is the rundown, So the problem is, a/c only kicks on when i jump the power to the compressor? any one ever have this happen before?

- i read i only have a low fill by pass front light
- i jumped the sensor by the pass side firewall no change in system funstion, im told thats a low pressure sensor
- freon pressure is high
- when i jump the + wire at the comp, comp turns on, a/c blows cold
- is the other sensor on the a/c line by the headlight a high pressure sensor?


trying to get a/c before all the real heat! THANX IN ADVANCE!

Yes the one by the headlight is the high pressure switch. They commonly go bad.
That will stop it from coming on.
Also the blower motor resistor will stop if as well.
The high pressure switch controls the A/C comp and cooling fan.

can i jump that switch to see if it is that? and i did read the other A/C posts so i was posting here to clarify. The blower worx fine, so ill start with the HP switch. Thanx for the reply.

It is a pain to jump the high pressure switch since it is 2 circuits.
If you have a junk yard near you get one from an 850 and test on your car.

do i need to purge the system to swap this?
and would one from a 960 swap?

No purge needed. Only a 850 and S70.

and if the system has to much pressure, would that switch stop the system from working?

Yes if it was overcharged.

thanx so much. the system worked last year fine. though this year it did not. it is overcharged, as i found out this year. so i thought it odd that it worked then and not now. the previous owner apparently overcharged it, so ill use the machine a purge some out and see what happens. THanx again for the info.

Let me know how you make out.

so what is the rating for the freon in this system? 2.2lbs?

1.63 is what the system holds.

so...here is the update. vaced and charged to proper pressure. Still no a/c. what i found is that there is no current going to the compressor. what turn the comp on? where does that signal come from? Any chance i could get wiring diagrams? Checking a relay was also suggested? does that exist. thanx for the help. And i did no replace low the high pressure switch yet. wanted to rule out cheaper options first.

The relay is in the fuse panel under the hood.

But my guess would have to be high pressure switch.