AC Is Quirky As Always

First thing, what comes to my mind is ice on and inside the expansion valve.
Did you ever try it with the front compartment cover removed, so that you can look how the expansion valve and surrounds look when the system quits?
If it's covered in ice, chances are good, that its internally clogged with ice as well.
After melting the system will work again.
Just a thought, but easy to diagnose.

Best from Germany
Martin

 

Have you examined/checked/refreshed the ground connection wire at the AC compressor clutch? If you have +12V at all of the terminals on the high/low switch(es) relative to ground, but the AC clutch doesn't engage, the trouble has to be somewhere in the wiring path from the high/low switch -to- V white connector -to- fuse panel PCB trace -to- Y white connector -to- engine bay connectors -to- AC clutch winding -to- ground = so wouldn't hurt to unplug/inspect/replug the V and Y white connectors too (the wire color of interest in both connectors is VM = green-brown). And same thing there -- if the VM wire terminal in the Y white connector is +12V relative to ground (you should be able to touch the VM wire terminal with your voltmeter when the Y connector is plugged in), but the AC clutch doesn't engage = wiring trouble is downstream from there.

Do you have a copy of the 328 wiring diagram book?

 

At best you have a voltage loss to the hi/low switches. Do you have a wiring diagram? If not that is step one. It should be a very simple process of following that circuit from the hi/low switches to the compressor. It is a very simple system.

Well Steve just said essentially the same.

 

PCB trace = the conductive copper paths on the fuse-relay panel printed circuit board.

Agree, but, if you get +12V at the high/low switch, the AC compressor clutch should engage (regardless of what other problems might be occurring).

 

Sounds like the switch is flakey. Try turning it on until it doesn't work then while NOT turning it off rotate the switch back and forth to see if it comes on. Or better, connect your VO meter to the output from the switch and verify that every time you turn it you get 12V. Could be the temp sensor thinking that it's already cool enough.

 

You have had this car for 32 years and it sounds like this has been an issue all along. I had this exact issue on a brand new one and it was simply a case of one of the spade connectors slipped out of the plastic plug and made intermittent contact. It was in the harness somewhere between the hi/low switch and the compressor. Have a look at the diagram and find all the plugs between those 2 components. I suspect you'll find one in the right footwell.

For what it is worth that was a common issue with those harnesses.

Hi/low switch is the one on the drier. It cuts off current if the pressure gets too high or too low.

 

As Brian said, the high/low pressure switch is mounted on top of the dryer under the front bonnet. In your #6 where you wrote: "There is 12+ volts at receiver dryer", I took that to mean that you do have +12V there even when the AC clutch does not engage -- if not the case, please clarify.

 

With that symptom, I can only restate that this indicates a break in the wiring path from the high/low pressure switch -to- V white connector -to- fuse panel PCB trace -to- Y white connector -to- engine bay connectors -to- AC clutch winding -to- ground. Make the same measurement (when it's not working) at the VM (green-brown) wire in the Y white connector:

If you get same +12V result there = problem is downstream from there.

If you get 0V there = problem is between high-low pressure switch and the Y connector VM terminal.

 

does the 328 ac work like the tr just ok or does it perform better ?

 

I maybe shouldn't have said "white" (as I'm not 100% sure of the connector housing colors), but you should have 8 longish single-row, multi-pin connectors (4 horizontal and 4 vertical) or, at least, places for 8 of them -- this jpeg shows the location of the Y connector position (it should have a VM wire on/very near the left end):
Image Unavailable, Please Login
PS Ignore the note in the jpeg - that was from discussing some other previous 328 issue.

 

Wow...if there's a chance that a 328 AC could be "better" than the tr's, the tr AC must be truly abysmal!

The best I could say of my 328 AC when I bought the car was, "poor." Admittedly, that was with R134 (previous owner). It could manage to make the cockpit "a little less hot." I drove the car 2700 mile in 2 1/2 days from Vegas to Chester, MD two days after purchasing it and I was sweating the whole trip.

It actually works reasonably well now, after a lot of DIY research and learning how to service it myself. Dealer/shop attempts were laughable results-wise. I'd call its performance now as "fair." It managed to keep me reasonably comfortable last year on a drive from Chester MD to San Antonio, TX.

 

outside temp last summer 95 inside was putting out 60 degrees so it was just cool i dont expect much from the ac from 80/s to early 90s cars

 

From about 1970 onward, any US car with properly functioning factory air could freeze you out of the vehicle. I never could understand why many cars from other parts of the world that were sold in the US were marginal AC-wise at least until the 90's.

I have managed to get my 328's AC (using propane-based refrigerant) to produce output in the low 40's with temps outside in the low 90's. The problem is that the evaporator does not have the capacity to move enough air volume. My wife's 03 MB S500 cannot get the output temps anywhere near that low in the same conditions - typically in the upper 50's BUT it can move so much air that it can hold temps in the car to the high 60's if you want to do that.

Adding to the mix, we all have various "comfort levels" as far as AC is concerned. I like the cabin temps below 75F; other folks are comfortable with them in the '80's. So an AC system that seems OK to one person, might be inadequate for someone else.

 

Traditionally European cars did not have as good A/C because their climate did not require it. American cars of the 70's are still a standard no one else at any other time have matched.

Also power windows. A number of years ago I had a senior mechanic under me at a Ferrari dealer. He once said quite correctly that he could go to a junk yard with a jumper battery and find an old Cadillac and the windows would work better than any Ferrari ever made.

 

What I find so odd about the windows is that there were countless better, proven, non-patented ways to accomplish the task. Why Ferrari did this Rube Goldberg cable thing with slow motors is just mystifying.

It's like the engineer had never even bothered looking inside an American door panel.

 

It seems, that the Italians were never really interested in these neglibilities. Look at wipers, heating, headlights and such things.
Though Fiat sold a lot of cars to the northern European countries, heating was less than adequate till the 80s.
They even started early, building cars in a new factory in Poland, where winters can get seriously cold. But they didn't care.

But why Ferrari didn't make a better A/C is beyond me. Italy -especially the south- is one of the warmer european countries.

Best Regards
Martin

 

I also have an '87 328 and an A/C system my dad and I rebuilt two years ago using r12. We agree 100% that this is not a air temperature problem but air flow problem. I jury-rigged some PVC pipe to blow the air directly on me from the round vents on the dash and this made a HUGE difference! Of course this was only a test and I couldn't leave them in there but it convinced me it's airflow/air direction.