A/C Pressure "normal" no cold air though....

tyr0981

tyr0981

New member
I guess 2014 is my year of tune-ups on the 4Runner! it's only been rock solid since 2004, and 250k miles....

Problem: A/C runs for a short time on startup for the first time of the day (putting out cold air) then after about 10min of running, the compressor will start turning off and on (engaging and disengaging) with just mildly cooled air.

So i bought a R134A refill can with a gauge on it, hooked it up to the LP with the engine around 1k RPMS, pressure goes up to 65-75 (slightly in the red zone on the gauge) and then the compressor disengages and pressure drops back into the green zone.

Any ideas? sounds kinda like air in the system according to some stuff i've read online..... Any advise would be appreciated!

thanks guys!
 
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bleed some off the HP port. Get the pressure in the green area. Too much pressure/134a is worse than having too little. The pressure needs to be in the green when the compressor is engaged. When the compressor is off the pressure should be well under the green zone.
 
tyr0981 said:
I guess 2014 is my year of tune-ups on the 4Runner! it's only been rock solid since 2004, and 250k miles....

Problem: A/C runs for a short time on startup for the first time of the day (putting out cold air) then after about 10min of running, the compressor will start turning off and on (engaging and disengaging) with just mildly cooled air.

So i bought a R134A refill can with a gauge on it, hooked it up to the LP with the engine around 1k RPMS, pressure goes up to 65-75 (slightly in the red zone on the gauge) and then the compressor disengages and pressure drops back into the green zone.

Any ideas? sounds kinda like air in the system according to some stuff i've read online..... Any advise would be appreciated!

thanks guys!
Click to expand...

To properly diagnose the system you need a set of gauges to hook to the hi and low side of the system. If you don't have those there's not much else you can effectively do, except what you've already done. The only other thing you can check is bubbles in your sight glass while the compressor is on. There should be almost none. Also, your suction line(the low pressure rubber one) should be cold. But again, if you find a problem, you'll need gauges to go any further.
 
Yeah no dual pressure gauges on hand.... First off, how could it get higher pressure in there when i've never added any R134 before? is it because it was hot out when i checked (~90 degree's)? also the engine was still warm (just turned off).

and if i bleed off pressure will that allow air into the system?
 
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Good questions, I'm not an AC pro but I can share my experience doing this to my 4runner a few weeks ago. I put too much r134 into my system because I was not careful about taking LP gauge readings only when the compressor was engaged. I had too much pressure and the AC compressor was clicking on and off frequently and the air was not cold. After taking another reading when the compressor was engaged I had too much pressure. So I released some from the high pressure side until my readings were in the green. I probably should have gone to a shop so they could capture the gas. Anyway, it fixed my ac temp. Now it's 40 degree air. After I released the 134a the gauge was in the green when the compressor was on and my air was cold.

I don't think moisture/air can get in when the high side is released. It should be a closed system, like letting air out of a basketball, no new air goes in.

Your symptoms sound similar to mine.

Now, how can your system have too much pressure if you never added any 134a? I do not know. I agree it is impossible to have too much pressure if 134a was never added, although it may have been because it was hot outside, I'm not sure.
 
alright, sounds like a good plan, i'll attack it gently and see what happens, i'd like to avoid the 120$ service fee, but me and my A/C are dear friends, and i miss it!

thanks you good sir!
 
take it somewhere and get it done right. get it connected to the machine and that will tell you what is going on. don't waste money and time with those crap cans from the auto part store. it could be a bad compressor, dryer, expansion valve, leak, you don't know.
 
01thunder said:
take it somewhere and get it done right. get it connected to the machine and that will tell you what is going on. don't waste money and time with those crap cans from the auto part store. it could be a bad compressor, dryer, expansion valve, leak, you don't know.
Click to expand...

Yeah i know, if the pressure is somewhat normal when i look this afternoon i'll throw in the towel and take it to Toyota, but venting excess pressure is free, since i already have the can and LP gauge.... The last thing i want to do is damage the compressor or break it even worse.
 
tyr0981 said:
Yeah i know, if the pressure is somewhat normal when i look this afternoon i'll throw in the towel and take it to Toyota, but venting excess pressure is free, since i already have the can and LP gauge.... The last thing i want to do is damage the compressor or break it even worse.
Click to expand...

To be honest venting refrigerant to the atmosphere is a 10,000.00 fine from the EPA. Not trying to scold you by any means, I am a licensed HVAC mechanic and Licensed Commercial HVAC contractor.. so hearing the words "venting" traumatizes me.
I agree with everybody else, a set of gauges will let you know what is going on being able to see high and low side pressures.

If the compressor runs fine at first then starts kicking out after some run time.. I would start with the condition of your condenser coil with is located right next to the radiator. If that coil is dirty, plugged, or beat up, air wont flow across it, thus not rejecting heat from compression, and cabin heat which will create high pressures on high and low side and even kick out the compressor on the thermal overload/temp safety
 
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I'll keep that in mind, i thought only the older R12 stuff (freon?) (really bad stuff) was super frowned upon...?
 
tyr0981 said:
i thought only the older R12 stuff (freon?) (really bad stuff) was super frowned upon...?
Click to expand...

That is correct. 134a does not destroy our ozone layer (protects us from all kinds of nasty sun emissions). Sure in a perfect world, we should capture all refrigerants but you're not helping destroy the earth with 134a. Luck! :banana:
 
Newer blends like 134a, 410a, etc etc are safer but the government now prohibits venting of all types and blends of refrigerants, but yeah newer blends dont contain chlorine which r22, r12, and r502 do but they still want to regulate in some sort of way.

Any luck with your AC? worse? better?
 
What year is your truck? Equipped with digital climate control?

I think your evaporator coil (behind the glove box) is clogged up by dust/dirt. Do you get good amount of air from the vents? If not, I think the evap. coil is clogged. Try pulling the blower motor out and inspect the inside evap. coil.
 
i pulled the squirell cage out and blew some dust off the fan, i get lots of air flow just not cool air after she warms up. No digital controls, it's a 2000 3.4 SR5, i hooked up to the LP and got the same wonky readings as before, goes up to just barley too high of pressure, then compressor turns off and pressure drops.

so, i don't know, don't have the gauges to figure it out... i'll pull the fan and look at the coil also, sounds like a good idea...
 
The suction pressure will vary with load and outside temps.

But the low side being in the mid to upper 30's on a hot 85-95 degree day is what I'd expect. The FSM should have a performance chart. My jeep does. And the spec is at 1200rpm with windows open.

How much air is your fan moving off the rad? A gauge set isn't that expensive. The high side pressure generally is 100psi + ambient pressure.
 
So i called around and the stealerships wanted a minimum of 120$ to 'Only refill the system!

so my cheap ass went to harbor frieght bought a (A/C R134A Manifold Gauge Set ) & watched a you tube video of what the hell to do with it. So the high pressure on my system was so high (engine off) that i couldn't connect the coupling! eventually i succeeded, with allot of lost fluid.... and when i started the engine up, idled ~2k RPM's in ambient temp of ~85 F, the Low pressure was under 30lb and High pressure was 210 - 225. so my system is a little low now (thanks to me) but the cold air is working again! not like it was, but working....

so according to the VIDEO CLIP i have a some kind of blockage in my systems expansion valve.... have any of you guru's the knowledge of on expansion valve cleaning or maintenance?
 
well quick search answered my own question. So if i have to replace the expansion Valve, do i need to worry about purging air from the system, or will refilling it with a can of R134A on the LP port be enough?

thanks for the input guys!
 
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