Hello all,

I was wondering if anyone in the 2nd Gen Dakota group (Or any other group for that matter) can assist me with diagnosing an AC issue. I have a 97 Dakota w/ 3.9L and when I got it the AC Pulley was seized up and bypassed. I've since replaced the Compressor, added in 2 DIY cans of R134a and nothing.When adding in the r134a, I never even seen the compressor engage, even when turning on the defrost the compressor doesn't engage. The compressor came out of a late 1996 3.9L Dakota, and has the same part number.

Any suggestions?

 

Use a gauge to watch the pressure, the A/C has a pressure switch and will not engage the compressor until the low-side (where you're adding) has sufficient pressure. It then kicks on the compressor and you'll see the pressure drop. Then you can fill to the proper level. When I worked on my A/C, it took 3 or 4 cans of R134a and that was without pulling anything, just fixing a leak (my high-side valve was stuck open, just putting gauges on it re-seated the valve and fixed it for me). Mine's a 98 with the 3.9. I would suggest, slowly putting in another can, if the clutch doesn't kick in after that, you may have either a bad pressure switch, compressor, or it's leaking out as fast as you're putting it in.

Make sure when filling your settings are on Max A/C with the fan turned up.

 

Ok, I'll try the additional can latter, but I do not have a gauge set. By chance, can one over pressurize the system? Causing things like a blown water-pump gasket? I only ask because as soon as I replaced the compressor, and began my AC Recharge journey I noticed my water-pump was leaking from the weep-hole so bad it was spraying the undercarriage as it was flung off the harmonic balancer. I've since replaced the water-pump (no leaks thus far) but wanted to ask before I dove back into trying to recharge the AC...

 

Yes, you can over pressurize the system, no it will have nothing to do with the water pump. That was simply a coincidence, overcharging the system also makes the pressure switch not engage the clutch, as over pressure could cause harm. You can usually grab the "big can" of r134a + oil and they come with a sort of generic gauge that should work well enough.

 

Cool, I do happen to have the reusable gauge for the DIY cans of R134a. Come to think of it, the gauge was just reaching the lowest point on the recommended charge level when I had to bail. The whole weeping water-pump thing made me feel like I was royally messing up somehow and didn't even consider it being a coincidence.

 

I will warn you though... Once you figure it out... You'll be cold. Literally, in my truck, with the A/C on and blower only on the second notch... I have to turn it off sometimes when it's ~92F cause it gets so cold, it almost hurts. Although, after a few minutes being used to the cold and having it off, gotta turn it back on. Makes getting out of the truck so much worse...

 

So, I've added in that 3rd 12oz can of R134a. The El-Cheapo gauge/refill hose gives me a fluctuating Psi reading of about 30psi, but never going above about 35psi. The I do not want to over pressurize / overcharge the system. The Chilton and Haynes manuals imply the AC System should be "serviced" by a professional but heck it only took 5 bolts and a single electrical connector to swap the old AC compressor for the one from the yard. That was easy, why in gods name is getting this R134a in and up to 50psi or 60psi so tough! Could I have cause a leak w/ the compressor swap? I do not recall a gasket being on the compressor...

 

When you changed the compressor

Did you add oil or was the new compressor full of oil?
Did you Pull a vacuum on the system?
Did you hold a vacuum?
Did you replace the drier accumulator?
Why was the the old compressor Bad?
Did the system have a catastrophic failure black death?

You cant just replace a compressor their are steps that must be done knowing why it was down is also important.

 

So to answer your questions 98DAKAZ,

Did you add oil or was the new compressor full of oil? I didn't do anything but remove the 4 long bolts, and the shorty holding the lines on the top...
Did you Pull a vacuum on the system? N/A Equipment Unavailable
Did you hold a vacuum? N/A Equipment Unavailable
Did you replace the drier accumulator? No
Why was the the old compressor Bad? As stated above, the old compressor was seized up and bypassed with a shorter belt
Did the system have a catastrophic failure black death? N/A Unsure of what exactly you mean.

 

I suggest you watch a number of videos on auto AC unfortunately most dont talk about the oil (pag 100) the system needs. If you dont have the proper amount of oil or correct oil the AC system will (over heat) turn the system black (burnt oil) and die.

Its like what happens to your engine if its run with low or no oil the engine over heats and dies.