2000 Dodge Dakota cools for 5 to 10 minutes then quits

[sunrise7]

So here is the condition:
1. First turn on ac, works fine for about 5 minutes... at 87F ambient, lowside = 28 to 30 psi, highside = 195 to 205psi, blows 58 to 60F air into truck.
After about 5 minutes, no more AC.
2. If you turn the AC Off and turn truck engine Off and wait 10 to 15 minutes, then restart truck, AC sometimes, not always, works fine again, but only for another 5 minutes.

I have evacuated the system, changed the drier/ accumulator and orifice, pumped it down and held vacuum, recharged.....
And it still behaves the same.
What other component(s) in the system might be suspect with this type of operation ? Compressor? Pressure or Temperature sensor? Dash switch?
Thanks ....`

[Cornbinder89]

All of the above plus whatever controls the heater. You haven't said if the compressor stops turning when it malfunctions. That need to be the 1st thing answered. Jumping ahead and changing parts is a waste of time until you know what is happening. The higher duct temp along with "normal" pressures leads me to believe that air control might be the cause not refrigeration system problem. Air is bypassing or being "re heated" leading to high duct temp. Bypassing the evaporator would make sense, and allowing the evaporator is reaching frost temp, and the controls are shutting down the the system to prevent frosting of the evaporator.
You have a lot of diagnosing to do before replacing parts.

[Cusser]

You haven't said if the compressor stops turning when it malfunctions. That need to be the 1st thing answered. Jumping ahead and changing parts is a waste of time until you know what is happening.

Last summer the AC in my 1998 Frontier acted similarly, and it was a slipping AC clutch after 245K miles in Arizona. The fix was to remove a shim under the drive plate, didn't need to unbolt the compressor or even remove the belt !!!

If your clutch drive plate isn't spinning when 12 volts positive is being delivered to the AC clutch, suspect this.

[Nacho]

Low or high pressure cycling switches fit the symptom. Jumper both with a paper clip and see if the condition goes away. Then replace the faulty one (low pressure most common)

[sunrise7]

Thanks for all the responses!
I will do some more diagnostic work.

[sunrise7]

7/17/2020 test………………………………………..
So here is some more information.
This is a 2000 Dodge Dakota V8 5 speed manual transmission.
Today I ran a test.
Ambient temperature during this test was 85F.
Before Starting the engine I put my gauge set on the system.
Lo pressure = 115psi Hi pressure = 115psi
Started the engine and turned on Max A/C…
Lo = 40 Hi = 105 Air at center duct = 54F
Ran for about 10 minutes at took these readings….
Lo = 30 Hi = 105 Air at center duct = 50F
Lo = 28 Hi = 110 Air at center duct = 48F
Lo = 26 Hi = 110 Air at center duct = 45F
Lo = 25 Hi = 112 Air at center duct = 43F
I then decided that maybe the engine rpm might be a factor since this being a 5 speed manual,
I do a lot of going thru the rpm range while driving, so we did some measurements at elevated rpm..
At 1500rpm, Lo = 18 Hi = 110 Air at center duct = 43F
At 2000rpm Lo = 16 Hi = 120 Air at center duct = 42F
Back at idle Lo = 28 Hi = 125 Air at center duct = 44F
At 2500rpm Lo = 17 Hi = 140 Air at center duct = 40F
Back at idle Lo = 28 Hi = 135 Air at center duct = 44F
We ran the engine for about 20 minutes, mostly at idle and the compressor clutch never disengaged !
Usually when I drive the truck, after 5 to 10 minutes the A/C shuts down.
We then shut the A/C off and turned the engine off and waited about a minute.
With the engine off, Lo = 65, Hi = 130
Then restarted the engine and turned the Max A/C on and the clutch would not engage, no A/C.
I am not sure what to check next…..

[Cornbinder89]

1st thing I'd check is the clutch gap on the compressor, with the compressor and engine off. You'll need a feeler gauge to see how wide it is.

[sunrise7]

I tried measuring the gap in the compressor clutch with a feeler gauge. Unfortunately, the drive pulley overhangs the clutch just enough so that it is hard to get a reading. I was able to slide a 0.025 inch thick gauge in the gap on an angle. But the actual gap in between seems to be larger than that.

What about the Lo side pressure I saw at 2000 to 2500rpm of 16 or 17psi. Would that cause a low pressure sensor reading to cut the compressor off ?
How low should that go ? What causes such low pressures ? Undercharge of R134a ? Blockage somewhere in system ?

Thanks!

[Cornbinder89]

I'd say 1st thing is to see if you can find a spec for the clutch gap, barring that I'd try and get it down to .015". Leave the charge amount alone for now, your center duct temps seam to indicate it is doing fine.
All my stuff is older and I am not familiar with light (car) stuff so don't know if there are shims that can be removed to adjust the gap or if there is some other way to adjust it or if the clutch has to be replace to bring the gap closer. The hotter the coil and plate get the weaker the clutch gets, then if it slips the heat rises fast and stops holding the plate all together. That is why gap is important.

[sunrise7]

Cornbinder89, Thanks.
I am going to buy a clutch kit off of Ebay for $38 and replace the old one. Doesn't seem too bad to do. And doesn't require evac and refill of the R134a. Looks to me that the trickiest part is getting the snap rings off that hold it all together.....

[Cornbinder89]

Let us know how it turns out please!