Air conditioning problem

[bradleyjon59]

I tried to charge my air conditioner and it wouldn't take the r 134. I did the bat disconnect to reset everything 5 times and no luck . I know the 134 is plugged in as the gauge shows 80 when the car is turned off but when I start the car it goes to zero . cked the fuse and it is good . what am I missing

 

[grumpin]

If there's not enough pressure in the system, it won't engage the clutch because the low pressure switch is open.

 

[77'911]

The classic models ran R12. You'll probably need to do a conversion kit and check the a/c recalls for the model. If I recall, Toyota had a recall for the a/c system on the early 4runners. We had the recall done at least a decade ago or more, ago, and the system still works fine.
It also helps if the system is evacuated(shows it hold vacuum) and a new receiver dryer is installed when recharging the system. Best of luck with it.
regards

 

[brittle]

New guy here, I can't post a new thread so here goes.

I need a method to jump the compressor so the system will take a refrigerant charge. Just got my first 4runner, a '95 auto v6. One of the reasons I bought it was how cold the A/C 'was'. A day after buying it, the a/c cooling started crapping out.

--the compressor clutch was still running but temp wasn't as cold. A shop said the system was properly filled with 134, but the expansion valve needed replaced, and then they evacuated the system for me.
--I replaced the exp valve, accum/drier, o-rings, added some pag46 and pulled a vacuum. Good to go.
--now with the manifold gauges hooked up and a can of 134 in place, the comp won't engage. Low side pressure is above 80. High side pressure went above 80 when I opened the can and both valves, but no comp kick on.

Yes, I downloaded the FSM. Again, this was a working a/c system and a shop verified that the comp was working but said the evap core was probably freezing up due to exp valve. I've read and read and studied and need a fix. I know where the a/c cutoff relay is and tested it as good. I know where the pressure sensor is located as well. I just need a method to make the compressor come on to draw up the refill of 134.

Thanks in advance if you can help a new guy out.

 

[grumpin]

What I did was pull a vacuum, leak test it for an hour. Then hook up a can and let the vacuum suck it in, it was enough to make the pressure switch so the compressor would pull the rest in. I used a bucket with warm water to put the can in to get it all out. Can't remember how many cans I used. Went by the volume required. Oh yeah, used a gauge set with a shut off for the service/vacuum hose, and an air compressor type vacuum pump.

 

[brittle]

Thanks. That's not working here. The compressor is going to have to be cheated somehow to activate it.

You know, two weeks ago I fixed my GM truck's A/C and you just have to defeat the pressure switch with a paper clip to get it to run. Is there not a way to do that on these trucks? The FSM says not to hot wire the comp to the battery, and it's so tight in there I don't think I could safely do it.

 

[brittle]

Ah, located the connector for the comp nearby the battery (hiding under a hose), so I jumped the compressor and started the uptake of R134. Low side pressure would drop below 30 so I would stop. When the high side started to advance above 150 it would slip back down, and the low drops too.

After drawing 2 12 oz cans, the high side still wouldn't stay above 125 psi. The low side kept dropping below 30. So I went ahead and let the low side drop to close to 20 and the high side never would broach 160 or so.

Sight window is all white bubbles when compressor is engaged.

EDIT: Added a little more 134 and the high side pressure will now go up to 200 and a little more (below 250). The bubbles went away. The compressor will still not work without jumpering.

temp: 80 degrees, humidity about 50%.

 

[grumpin]

I don't know about your 95, but on my 87 I can jumper the pressure switch under the dash. If you can that will help troubleshoot.

 

[brittle]

Saw a post about jumpering the A/C CUTOFF RELAY, but I wasn't able to. The relay works. I applied 12V from pin 1 to 3, and it activated across 2 and 4, but no compressor function.

Also, I see that there are 3 relays under the hood, CNDS #1, #2, #3 which suggests a condenser fan with different speed relays, but if there's an electric fan under the hood, it's hiding where I can't find it. I've only looked while the engine is running.

 

[brittle]

Fiddled with it and ended up at about 34 psi on the low side with the high side close to 225, temp 86 with 50ish% humidity. A/C works pretty well.

Locating the reason the compressor won't func on it's own will have to wait until I have some more time.