Rebuilding the AC system on my 94 ranger xlt. Saw a video where he had a 94 but it was the 4 cylinder. His system took 7 oz. Of PAG oil and 22 oz r-134a. Would my system be the same? Or how could I find this info?

 

Info I'm finding from 2 sources says 36 oz of r134a.
so a lot of it.

 

Yes, 1994 show
36oz R134A
PAG oil 7oz

 

thanks

 

New problem.
I pulled vacuum for an hour. Then I started filling the freon. Only got about 3 ounces in and cant do any more because the compressor won't kick on. So that's my project tomorrow. Why won't the compressor kick on? I'm thinking a fuse or relay or maybe the high or low pressure sensors?

 

Reading ac diagnostics stuff I think I know what I did wrong. I started adding refrigerant with the engine turned off. I added about 1.5 oz before starting the truck. The low side pressure switch is part of the AC cut off circuit. If the pressure isn't within range it opens circuit. That low side pressure went up fast Without engine running. I went to start engine because the pressure in the can was matching the line pressure so it wasn't coming out.
might need to manually jumper the compressor clutch tomorrow to check it and also to suck that pressure off the low side so system will register it again.

My theory so far anyway. Other than that there are a few fuses I want to check and a relay.

 

Yes that makes sense, low side switch prevents compressor from running "dry"(no oil) so would prevent start up of compressor

 

I'm debating just taking it to a shop and forking over the $160 recharge fee. This thing is so fickle. Beyond my knowledge with adding refrigerant. I've been adding and subtracting freon for hours and cant seem to keep compressor running for more than a few mins.

 

I jumpered the compressor and added 18oz coolant. Easy blowing nice and cold but when I tried to connect compressor harness nothing. I checked the ez fill can top gauge and it said 50psi low side. That seemed too high so I drained a lil. Still 50psi. So I hooked up the manifold gauge set I rented from autozone. I hadn't been using them because the line leaked. But figured I'd get a better picture. Couldn't figure anything with those so left them hooked up. Forgetting how bad they leak. Turns out the relay was acting up so I fixed that but in the meantime I check gauges with engine off now both low and high side are 20psi. I got compressor to fire. But only for about 20 seconds then it kicks off. I can turn ac off then back on and compressor runs for another 15- 20 seconds and kicks off etc... that's about where I'm at now.

 

Guess what I could do is spend the 35-45 to recover r134. Then buy 2 more cans of it for about $7 a can and be back where I started. Then rent a different set of AC gauges that dont leak.
at first I thought my install was leaking because it wasn't holding vac. Turns out it was the gauge set. With both sides hooked to themselves with valves closed and service line hooked to the vacuum. Like this it doesn't hold vacuum.

 

Got refrigerant up. To normal pressure range. 50psi low side.
compressor clicks on as long as engine isn't running. As soon as I start engine it kicks off and stays off.
I checked both high and low pressure switches. I jumped both switches with a wire ac compressor did the same thing clicked on then when I started motor compressor ran for a few moments then clicks off. With both switches disconnected and jump wired.

I swapped relays around and same thing. I'm wondering how the wide open throttle/ ecm works? Could the ecm think its getting wide open throttle and shutting compressor down? Could it be a bad ECM?

 

Cab fuse 17(12v key on)----------------AC switch on dash-----------------------pressure switch 1----------pressure switch 2------------------AC WOT relay-------------AC Compressor---ground

The AC relay is a 5 pin, so pass the 12v to AC Compressor when relay is OFF
The Computer will ground the WOT relay to activate it and cut 12v from AC compressor

Yes it would do that when TPS(throttle sensor) was at Wide Open Throttle(WOT)

Simple test would be to unplug AC WOT relay when engine is running you should feel it "click" closed if it was "on", and then plug it back in and it should "click" on again

5 pin relay diagram: https://i.pinimg.com/originals/87/2a...504c2c7463.jpg

If you pull out the relay you will see the slots
If you use a jumper wire between 30 and 87A, not 87, then AC compressor relay is hot wired, computer is out of the loop

 

Thanks RonD.
AC blows cold now.

It wont cut out WOT but works.

 

Cool

But that jumper setup shouldn't work, lol

Thats 30 to 87 and 87 shouldn't be hooked up to anything, so odd

 

the middle pin is empty on this relay for some reason.according to the relay left and right pins are the ECM controls. That connect the top and bottom.

 

Actually maybe I should jump the 85 and 86? That way I'm not cutting out the pressure switches? For safety reasons?

 

Actually never mind that wont work because it wont power the relay magnet. Problem is the top and bottom pin jump is basically just connecting the compressor to the battery. I cant cut the ECM out without also cutting the pressure switches out. Not from the relay anyway. That continues loop ( ground - ac switch - low pressure switch - high pressure switch - ecm - relay - positive batt lead) that whole circuit just energizes the relay. And the relay basically jumpers the compressor.
so maybe the way to cut out the ECM is to literally cut and splice the dark grn/ orange and pink/ red wires together?
Then plug in relay? I might need to physically remove the ECM from the chain?

 

WOT relay 85 and 86 are not connected to pressure switches and in any case if you ever jumped 85 and 86 that would be a DEAD SHORT on any relay and would hopefully just blow a fuse, worse case would be a wire would melt and start a fire

So never jump 85 and 86 on any relay