Seems to be just this thread (or subforum?) links in following thread work, for example Fog lights with high beams... the easy way

Yes I have. That’s how I got only 5v on pin3 to ground connected. I disconnected the harness from the amplifier to thermistor and back to the dash, no issues there. I’m going to do a continuity test from the different pins to the endpoints, like pressure switch, clutch and so on….

Edit: Had the wrong year 1997
This is 1999 So I deleted what I could @badluck and T4Rscott will have to delete their replies

1999 EWD of AC in photos [8]

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I quickly glanced the thread, and I understand you don't have manifolds to check the pressures and what happens when you press the gas?

You going on blind if that is the case. There are cheap manifold sets on amazon that you could use for this time, might not last and might leak, but at the least you would see what's actually happening and not go blind. Impossible to diag A/C without manifolds

When I step on the gas pedal the clutch engages, and when I let off, it will stop.

I understand what you are saying about the gauges. However, the pressure was fine at the time it was serviced and was still doing the same thing. I will look into a set from Harbor Freight.

I would just verify with gauges.. As my limited AC wouldnt work at all. Thought all i just have a bad pressure switch because the PO had the ac disconnected and I figure the Switched just failed. So when I took it to my buddys to have it evacuated to replace the switch... I only had 10 pounds psi. My 1997 limited has a leak. Hopefully the dye in the system will so me where this leak is.. I changed the switch anyhow. Put a almost 2 cans of 12 oz refrigerate in and See if i can find my leak.

Yours could be perfect pressures. It will rule it out.

I think if your system is all checkes out and your amplifirer is good.. You have a wiring power issue somewhere ad that is all that is really left. :-(

I did finally get the electrical diagrams in photo form on this thread for the 1999 model year..

Ok, it’s the time you’ve all been waiting for, 😆

I put the gauges on it, and here’s the results:

With the engine @1500 rpm, AC on, fan on HIGH and temp at max cool,

Low side was 30-35 psi
High side was 350-400 psi

When the engine returned to idle:
Low was 80-85 psi
High was 200-225psi

The outside temp was about 85 and to was 45% humidity.

According to the FSM, it could be the condenser or the expansion valve.

Let me know what you all think.

Scott

Your high-side pressure at 1500rpm is way too high and the low side is a bit high. At idle, your low side should be roughly 30.
Possible causes: weak fan clutch or overcharged system or partially plugged condenser, which could be something internal or the fins plugged by dirt or mud.
A bad expansion valve usually results in the low side being very low or going into vacuum.

Ok.. how was this system refrigerate amount verified.

Was the system evacuated and the proper amount of refrigerate pushed in? Or are we just reading gauges psi and tweaking it this way?


Because the you pressure can be right on the edge where the safety switch it tripping out.

Plus what does your site glass looking like? As that glass can tell you alot how the ac is system.

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I can only go by the shop that did the evac and refill. They used a Robin Air machine.

I looked at the condenser and it is rough. I remember when I did the radiator, the fins were popping out very easily due to age and corrosion.

Those pressures at idle and 1500rpm lead me to believe your system is overcharged

And if it's overcharged it can blow the compressor [ yes I did that before ] You can't tell how much refregerate is in the system.

I blow a compressor using gauges. I had a bad Condenser and naturally way too much refrigerate. Blew the compressor and it was over. Pressure equal on high and low.

If your ac system. Wasn't evacuated and the proper amount of refrigerate put in. Then that's were you start.

Unless your tracing leaks like I am. You really have to watch the refrigerate amount.

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What the sight glass can tell you.

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It was filled appropriately according to the sight glass.