A/C expert needed.

[Beans71086]

I have had no ac since spring rolled around, figure it just needed a charge so I went to the auto parts store and bought a charge kit with a gauge. Start the truck with the ac on max cool, plug the gauge in (on the LP side) and it's in the "danger" zone at 80psi.

So, what can I check before assuming it's the compressor?

 

[Stroked777]

Is the compressor even kicking on? If so the pressure should drop when it does kick on. And if it doesn't drop and the clutch is engaging your probably looking at a compressor

 

[Mixedbreed]

Check the pressure with nothing on and the system in a stable state. Should be close to the same as ambient temp. The pressures should be the same on high and low side when the system is completely off and it's been stable for a while. there's no reason the low-pressure side should be that high unless there is a blockage somewhere but the blockage would be in the Evaporator. any other symptoms that you can talk about?
The only other thing I can think of but it really doesn't seem feasible is your receiver drier desiccant bag exploded and put non-compressible's in the system but that would even be a highside failure because the AC system is high from the compressor to the thermal expansion valve and low after the valve to the inlet of the compressor
Like it was asked before, does the compressor cycle normally? Even if the compressor is bad the low side should never get in the danger zone because there's nothing to raise the pressures in the system.

Do the fans turn on when the ACs kicked on?

 

[StockCar#10]

Could be a plugged orfice tube

 

[Mixedbreed]

No orifice tube on a ford system.

 

[fordfreak4life]

Low pressure switch could be shot

Sent from my SCH-R530X using Tapatalk

 

[Derkperk]

R-134a is at 80 psi when it's 76* ambient. Telling him the pressure should match ambient tells me you have no clue what you are talking about. Don't give advice on something you are guessing at. If there was a "blockage" his suction would be low not high. Oh, an the "danger zone" on one of those dummy gauges is for when the system is running.

I would guess that your compressor is not running. Weather it's the clutch, mechanical or electrical side or your pressure switch has failed. Jumper out our pressure switch to see if the compressor starts and we'll go from there.

 

[Big Angry Hillbilly]

No orifice tube on a ford system.

You're kidding, right?

 

[Big Angry Hillbilly]

Check the pressure with nothing on and the system in a stable state. Should be close to the same as ambient temp. The pressures should be the same on high and low side when the system is completely off and it's been stable for a while. there's no reason the low-pressure side should be that high unless there is a blockage somewhere but the blockage would be in the Evaporator. any other symptoms that you can talk about?
The only other thing I can think of but it really doesn't seem feasible is your receiver drier desiccant bag exploded and put non-compressible's in the system but that would even be a highside failure because the AC system is high from the compressor to the thermal expansion valve and low after the valve to the inlet of the compressor
Like it was asked before, does the compressor cycle normally? Even if the compressor is bad the low side should never get in the danger zone because there's nothing to raise the pressures in the system.

Do the fans turn on when the ACs kicked on?

My brain hurts after reading that.

Your knowledge of air conditioning in an automotive application is not adequate to diagnose this problem.

A super duty doesn't have an expansion valve.

 

[Mixedbreed]

Okay angry hillbilly. What is it then? And what type of system is it?

 

[dieselflash]

Well I am a Ford tech, orifices are used in 99-07, 08 to current have an expansion valve. No need to get testy boys.

 

[Mixedbreed]

R-134a is at 80 psi when it's 76* ambient. Telling him the pressure should match ambient tells me you have no clue what you are talking about. Don't give advice on something you are guessing at. If there was a "blockage" his suction would be low not high. Oh, an the "danger zone" on one of those dummy gauges is for when the system is running.

I would guess that your compressor is not running. Weather it's the clutch, mechanical or electrical side or your pressure switch has failed. Jumper out our pressure switch to see if the compressor starts and we'll go from there.

So 80psi at 76 is not close enough to ambient?? But I will admit at 6 am this morning I missed the 80 psi as the danger level. And I agree it is a compressor or associated circuit. Maybe coffee first next time.


I, like you, am just trying to help. Internet diagnosis isn't a perfect science.

 

[Fordguy100]

It will read that pressure if there is 5oz in there or if its fully charged.

OP, you need to get a set of manifold gauges, either buy or rent (I have rented them from vatozone before). This will tell you your low and high side pressures, with only a low side reading from one of those fill cans, its very hard to trouble shoot.

Like said, make sure the AC compressors clutch is engaged, and the AC pump is spinning. Did your system have any pressure it it at all when you first started filling?

 

[Beans71086]

Thank you everyone for your help!

Collected some new info, the pressure after setting all night was around 75. Started the truck, engaged the ac (compressor is running) and the pressure didn't move. I unplugged the sensor (LP sensor?)on top the canister thing next to the firewall(evaporator?) and the compressor turns off, promptly turns back on when I plug it in.

Ford guy- I didn't add any freon to it because the pressure was so high.

 

[CATDiezel]

A real set of gauges for starters. But also. Check the AC clutch relay. If all else fails. Build a jumper and manually engage the compressor. Since you will be doing it manually watch the gauges if things get wild like below 5 psi on the low side or closing in on 400 psi on the high side kick it out. That will tell you if the business end of the system is working.

If it is. Then back track from there. Could be in the cab via the temp control module if it's auto climate.

I'm going to guess relay.

There are alot of things to check. But if it's over your head then you'll have to bite the bullet and take it to an AC shop. Not just a regular garage. Most regular garages don't take the time to properly fine tune and balance an AC system.

 

[Big Angry Hillbilly]

Okay angry hillbilly. What is it then? And what type of system is it?

It is a CCOT SYSTEM.

CYCLING CLUTCH ORIFICE TUBE.

 

[Big Angry Hillbilly]

My 08 truck has an orifice tube as well.

 

[Big Angry Hillbilly]

CCOT was used until 2010.

Txv usage began in 2011.

 

[Beans71086]

A real set of gauges for starters. But also. Check the AC clutch relay. If all else fails. Build a jumper and manually engage the compressor. Since you will be doing it manually watch the gauges if things get wild like below 5 psi on the low side or closing in on 400 psi on the high side kick it out. That will tell you if the business end of the system is working.

If it is. Then back track from there. Could be in the cab via the temp control module if it's auto climate.

I'm going to guess relay.

There are alot of things to check. But if it's over your head then you'll have to bite the bullet and take it to an AC shop. Not just a regular garage. Most regular garages don't take the time to properly fine tune and balance an AC system.

The first picture is with the truck shut off after being a 1/2hr.

Second pic is with the truck and compressor running.

 

[Beans71086]

.... Ok the picture below is with the truck shut off, the on above is running.