AC guys please help

I bought my truck knowing the ac wasn't working right (warm air from vents), so today I finally got around to checking it out. Bought a manifold set and checked the pressures, below are the results.

Ambient temp = 70 degrees, Humidity about 50%

Engine Off:
Low side =60 psi
Hi side= 68 psi

Engine on (Idle)
Low side = 0 psi
Hi side = 75 psi

Engine @ 2000 rpm
Low side = -7psi (negative psi???)
Hi side = 75 psi

I've been reading up on possible issues and everything points to a clog of some sort in the system. Anyone wanna take a stab at interpreting these pressure readings? Seems the refrigerant isn't circulating. The compressor runs fine, I can see the center thing spinning on the compressor when the AC is on, but I haven't ran it long enough to see how long it cycles on and off.

Any guesses?

 

Dunno bout the pressures but is that with the ac on? Sounds like low r134

 

Expansion valve stuck shut.

 

Yes AC on with blower on 3.

 

take it to an automotive AC repair shop

 

Is this a common issue? Could it be a clogged condensor too?

 

Now why didn't I think of that.

 

Its a sealed system. Typically the only time there is debris to clog anything is when the compressor has let go internally. Then everything needs flushing.

 

....I don't know if you caught the sarcasm in the tone of my voice. But I don't usually take any of my vehicles to any mechanic unless absolutely necessary or I have exhausted all other options, hence my original post.

 

Makes sense. Thanks. So I guess replace the expansion valve and see if that helps? Anything else to check before doing it to rule out other things?

 

Gonna second the low r134 vote. The important question is why is it low. I don't know about Toyota, but a lot of manufactures include florescent dye to help with finding leaks. Do you have a black light? In a dark room, garage with the door down or after dark, shine it under the hood and around the evaporator to see if there are any obvious leaks. The dye isn't totally effective though. My wife's car has a leaking compressor seal that hid the dye. I took it to 3 AC shops and not one of them could solve the problem, but they were more than happy to take my money.

 

Id try to top off first

 

Absolutely.

 

Can you tell if the Clutch is engaging or not? Your high side seems very low for running.

 

The system is empty, it needs a charge

 

Yeah i would try adding before doing anything. But if that doesn't solve it your gonna want to take it somewhere anyways unless you have a vacuum pump or other A/C tools because you need to capture whatever r134a is in the system and determine its weight to determine how much needs to go back in, and you have to remove all air from the system because air does not work well in A/C systems.

 

Sure.

That the compressor is actually engaging and you see pressure differences when it is.

Try adding some refrigerant as others suggest and see if things change

The line to the evap should be cold, the line out from the evap should be hot

I 'jumped' to the expansion valve based on your 'blocked' system reference. Clearly, yes, you should try several other low/no cost items before moving to the expansion valve.

IF you have to open the system, you'll need a new accumulator and a vacuum pump too.

 

Had the same readings just yesterday. Its needs a can or 2.

 

system is empty take it to an auto AC shop for a Freon recharge and they will also professionally evaluate your system, grasping for straws wont get your AC system working properly