1991 Dead A/C

[AuroraGuy]

My A/C worked 2 weeks ago. No issues whatsoever.
I had a new condenser/recevier installed last year and the system was evacuated - tested and then charged. worked great.

Well now, nothing.

No clutch
No idle up
No rad fans spinning...

The light lights up on the A/C switch but thats all. Its totally dead.
Checked fuse - ok.
Checked clutch on compressor. Not shorted. Not open and relay
tests good too.

Well here is what I checked so far.

I checked the pressure switch located in the frunk but just infront
of the evap box. It has 0 ohms (continuity) right now.

if I unplug the switch and turn on the iginition, the rad fans go nuts.
With the pressure switch connected - they are quiet.

Looking at the BGB (AC-42) what does this 'continuity' mean?

They list 2 pressure switches (confusing) but based on 'continuity'
it "appears" there should be adequate charge - unless I am misunderstanding.

Dual pressure switch: More than 33psi or less than 299psi = CLOSED
High pressure switch: unclear to me.

From the way I take it, this switch should be 'open' if the system has too little or too much pressure. - ie: system empty, switch = OPEN or no continuity...

I know I need a test flange - but in the mean time I was hoping to possibly determine something from reading the pressure switch.

The odd part? - with the system connected, the pressure switch is closing its contacts right now. If this works like GM's systems, when its contacts are closed, there is pressure (not too much or not too little) - If I remove the pressure switch connector - it no longer can complete the circuit yet nothing changes but for the RAD fans spinning....so I would presume that this would tell the amp that the system has high pressure and needs additional cooling - therefore turn on the fans.

At this point, I think its safe to assume based on this paultry test, that as far as the switch is concerned - the system HAS pressure.

Any thoughts on that guys?

I think this could be (at this point) one of 2 things.

1. Bad A/C switch (although its only 2 yrs old)
2. Bad A/C amplifier

Now, I am all for removing the A/C AMP and looking it over but where the hell is it and how can I remove it w/o ripping out the entire cabin HVAC assembly?
I am hoping there is a way to remove this AMP w/o discharging the A/C system!



-JD

[PHOENIX]

Just so you know, Toyota has a Recall on the 91 MR2 involving the A/C system, you should call your local dealer to see if you can get serviced for free (you can search this board too for the number, its here)

[AuroraGuy]

Roger that. The prior owner had the recall done.

BTW, it did turn out to be a total loss of FREON.
I really found that odd.

Blown o-ring under the car near the fuel tank.

$225 for parts/freon/labor

I didnt think that was all that bad, considering they only charged me
1hr of labor ($95) and worked on the car over 3 days.

[PHOENIX]

Thats not a bad price at all considering it was A/C work.

alteast its fixed now

[charto911]

check the ac poll

[Dance_Business]

Originally Posted by AuroraGuy

Roger that. The prior owner had the recall done.

BTW, it did turn out to be a total loss of FREON.
I really found that odd.

Blown o-ring under the car near the fuel tank.

$225 for parts/freon/labor

I didnt think that was all that bad, considering they only charged me
1hr of labor ($95) and worked on the car over 3 days.

At the dealership? I just bought a 91 NA and it needs servicing, plus the two recalls( AC and steering wheel). I think it's a leak and nothing else.