See if the compressor is locked up, try to turn the end "most forward" witch
is the clutch ring. It should turn by hand both directions and it will have
slight resistence but smooth.

 

It turns fine. I'm not getting power to activate it. No power to the connector that plugs into the clutch.

 

I don't want to read the whole thread. Check and replace the low pressure switch, it is what activates the pump clutch and the high pressure switch stops it.

Mine has gone out twice. Sometimes it is a loose connection, wiggle the pigtails for the pressure switches and see if it comes on.

 

I can't find my service manuals, but IIRC there is a low pressure switch somewhere in the A/C circuit. It saves the compressor from damage in case of a leak of refrigerant.

I have a bad pump seal, and if the pressure gets low enough, the clutch will only cycle for a second or two before shutting off (if it cycles at all). $5.00 worth of R134 and all is good for a few months

 

the plug that goes into the accumulator is the low pressure switch. to check to see if the compressor works you can unplug the sensor and use a piece of wire to jump across the plug and your compressor should come on when the ac is on, if it doesn't, then you have a problem elsewhere. if it does come on when you jump it then you are low on freon or the switch could be bad.

 

Guages would really help, you can usually tell imediatly what is going on with an a/c system by the guages, sounds to me like you ahve lost just enough freon for the pressure switch not to kick it back on...

 

:whs:

Normally I see static (A/C not on) pressure within 5-10psi of the ambient temperature on a properly charged system (R134a).

 

I had a similar problem, but it was the shim in the clutch. Here is a copy/paste from another forum:


"The blend doors on these trucks are electronically controlled. That being said the most common reason for poor cooling is the system being low on refrigerant, the compessor clutch not engaging, poor fan clutch performance not getting enough airflow across the condensor at idle, or the cycling clutch switch (aka low pressure switch) going bad.
To start, NEVER try to charge an ac system without a manifold gage set with both low and high side gages on it. Using those wally world one gage wonders is like flying blind. The high side pressure tells you a lot more about whats going on than the low pressure side.

Usually a ford leaks at the springlock couplings and the compressor shaft seal, random oily residue around an ac fitting is usually a sure sign of a leak and also if you see a ring of oil slung around the compressor clutch area (hood, radiator hoses, etc) thats a good sign also.

Fan clutches and poor airflow problems can be checked pretty easily if you have hig and low side gauges, when its really hot out let the truck idle and when the high side starts to really climb (250-300) spray the condensor with some water and if it drops really fast then theres an airflow problem.

The low pressure switch is pretty common also, this can be easily diagnosed by looking at the compressor hub while the ac is on and its blowing hot. If its not turning, theres a problem! First try to take the handle of a hammer and tap the hub in, if it pulls in then it needs to have a shim taken out fron under the hub. You can try to wiggle the connector and see if it comes on, be sure to check for broken wires at the switch. If it doesn't and you have adequate low side pressure (over about 40 psi should kick it on) then it should be replaced."

 

May not help, but mine did the same thing and it had a short in the pressure switch. I could turn the a/c on and wiggle the wires and it would kick on.

 

Good info. I removed the shim last fall and it has been working fine ever since. Now that it's getting warm again it is a no go. The clutch is not clicking on or spining at all and no power at the end of the wire where it plugs into the clutch. Could be low on freon like a few have posted, I guess I just need to have that checked first.

Thanks for the help.

 

Can somebody tell me what are the guage numbers are supposed to read when a system is running and charged properly?

Blowby,
Are you checking iside the plug for voltage? Check down the harness a lil bit. I just replaced both of those plugs near the compressor, one of the wires was broken free inside the plug.

 

I did check at the plug connector. I'll try down the wire as well.

I read the high should be 200-250 and the low 25-40 running. Correct me if this is wrong for R-134a.

 

Your correct on the pressures. Blowby you should get a piece of wire and jump the low side pressure switch b4 you get hosed with some tech tellin you what is wrong. This way you can go right in and tell them exactly what you want done and not have charges for stuff you dont need.

 

Can you elaberate on the jumping? I guess the pins on the clutch need a hot and ground, correct? Or is there an easier way to do it.

 

not the clutch but the low pressure switch. Do that and see if it makes the compressor kick on.

 

Where is it located?

 

should be on the passenger side close to the fire wall. What year is your truck and do you have a 7.3? If you do ill go and look at mine and tell you where to look exactly

 

99.5 - 7.3

 

ok

the low pressure switch is goin to be located on the dryer next to the blower on the fire wall. And the high pressure switch should be next to the compressor on the line running into it.

To check it all you have to do is use a piece of wire and just jump the conector to make it click on. If it doesnt do anthing then there is goin to be a bad wire. But it should make the compressor kick on. If it does then you know you have a bad low or high side switch.

 

Thanks, I'll give it a try.

 

No prob. Im here to help if i can lol

 

One more question. I have my system charged to 240 & 45 which is good. I have heard that the actual compressor should not have condensation forming on it when the ac is on is that true? I cant remember where I heard that info but mine does have water forming on it and is cool to the touch. I dont think that is right.

 

No its fine if it does that. Idk why sombody would say that. You have Freon being ran through the condenser getting cooled down so its goin to get WAY colder than outside temp. Its fine that its sweating tho.

Nothing to worry bout on your truck.

 

Jumpered the switch and the A/C clutch activated. Guess I'm just low and need a recharge.

 

Probably but you need to check the pressure to be sure. The switch is supposed to open at about 25 psi and close at about 45 psi. So if your pressure is 20 you need some juice and your leak fixed. If it is 70 you need a switch.

 

The pressure was 0. I used

I used the whole can and the guage rises to 40 and the clutch kicks in and the guage drops to 25 and the clutch kicks off. It will keep doing this as long as the A/C is on. Does the pressure level out when the right amount of freon is in it? Do I get some more to add?

 

It needs about 48 oz of 134a to be full. It probably won't stay full until you fix the leak. What is in that can besides 134a? The pressure will always cycle between 25 and 45 but it does it with less frequency on a fully charged system.

 

Pressure should never level out.

Its actually suposed to cycle. From bone dry it should hold 42 ounces which whould be 2.65 normal size freon cans worth.

So 2 1/2 cans of freon.

The low side which is what your seeing the pressure on will change from 40 to 20something as the compressor cycles on and off. Its suposed to cycle just not that often.

 

Oil (lube) with System Safe leak repair.

Sorry wrong can. This is what I used it says 18 oz's

 

Oil (lube) with System Safe leak repair.

I suspected that was what you were going to say. If you take it somewhere to be repaired and it still has refrigerant in it at least be considerate enough to tell the shop that you put sealer in it.