A/C Temp Data 1982 help

[gr8vet]

Still chasing ac data and for the life of me cannot find anything online.

OEM system, rebuilt compressor, 3 years old now. I did add a new orifice, oil, o rings, and a new dryer. Completely flushed system with required cleaners.

Temp at vents a freezing 65 degrees. LOL

Temp going to compressor 98 coming from cabin

Temp coming off compressor headed toward condenser 139

I installed the system, evacuated it for 1 hour, charged with r134 to about 40psi on low side. No leaks. Showing 100 psi on low side with compressor not running

Now, what should all these numbers really be? Obviously something is not good. Wondering if the rebuilt compressor was not a good idea, or air in system, too much 134, not enough???

Thanks in advance.
tt

 

[Twin_Turbo]

Why not take it to an AC shop? I think the service manual should have the data you need. I'll check if it's in there.

 

[gr8vet]

Hey TT, thanks for the reply. Unfortunately I am 60 miles from any decent AC support, kinda forced to do this stuff on my own.
From what I have gathered, I should see about 15 to 20 degrees difference between in and out of cool air. The difference in temp on each side of the dryer should be about the same. Which is about what I have. 4 degrees difference. No doubt the OEM rebuilt compressor is not as efficient as a new one.

BUT! I think I made a huge boo boo. The looser I am, I had the recirc air duct sealed off. When I started reading a year or so back about sealing off these areas, crap, I sealed anything I could find. I had stuffed some filler around the intake for fresh air too, but not very well. Both of these vents work with the vacuum system, so I did have that going for me. I believe if I seal the fresh air very well, and open the recirc air, which I think I am right that it comes from passenger floor vent??? I may be good. No telling where I was taking recirc air from, I guess from every leak it could find.

I'm I correct that the recirc air to the fan comes from the floor vent???

Not sure what I may find but in my wife's Expedition, the difference between fresh and recirc air must be 15 degrees better overall.

Thanks Friend, hope all is well over yonder.

tt

 

[mrvette]

The suction side of that squirrel cage blower is in the center/rear away from the motor, into the plenum formed by the fender and some cowling, the flapper under the WSW trough you can barely get to, mine has been sealed for many years, the flapper up under the toe kick panel on the pass side, was entirely removed, the vac control line plugged, mine is on permanent recirc...but it's a convertible, anyway....

Long time ago, I cut out the fender liner to ease the access to the blower motor, and it's a C4 motor with heavy up wiring on both ground and high speed feed wire to the relay....

you almost need to do that liner cut to be able to clean the plenum for junk blocking airflow....on the pressure/fan side of the evaporator....

 

[010752]

Gene is correct about the recir setup, that's about the best you can do. Seal all the joints with a good body seamfill to make that fender/cowl plenum as air tight as possible , leaving the water drain at the bottom open.
Seal off the fresh air hole completely in the cowl. If you remove the fresh air flapper and can, you can wiggle a normal household vacuum hose down there and get almost all stuff out. I've found bolts, parts leaves etc. Make sure your drain is open and degrease and wash the plenum (watch recirc area) and repeat untill clean. The you can seal from the recirc door a bit better.
Cooling is all about removing heat, reduce the heatload (recirc) and it helps a bunch.

The only temps that usually mean anything are ambient, biggest flow dash vent (usually center), evaporator inlet (after oriface tube) and evaporator outlet tube.
The temps you posted just tell me that it was around 86° outside that day. h:
Pressures (high and low) rpm, car location, and temps are needed to diagnose.

 

[82SR71]

I changed to 134A recently. My mechanic changed the cycling switch. The 134A requires a different switch to allow for 134A operating pressures. My A/C is very cold.

I got the switch from O'Reilly. PN 36674 Cycling switch.

1982 C-3. Mostly stock with damn cold air.

 

[mrvette]

I changed to 134A recently. My mechanic changed the cycling switch. The 134A requires a different switch to allow for 134A operating pressures. My A/C is very cold.

I got the switch from O'Reilly. PN 36674 Cycling switch.

1982 C-3. Mostly stock with damn cold air.

To measure that sort of stuff, I tie wrap a little button gauge with the stem on it, to the center duct output...actually I have one there permanently....

then use another one in the floor area for a return of ambient air temp....

the two of them track very well with each other, and my Fluke setup and other thermometers.....I check them all to the boiling point in a pot of water on the stove....which is about as accurate I can get on the upper regions....

anyway, if conditions are near ideal I can get 25f+ drop across the a/c evap coil.....fan on high speed, and it's a C4 fan & wiring, giving much more blow than 'normal' for a C3.....I have a '88-91 serp drive and compressor, the expansion valve is new, and the POA valve had the end nut tweeked a couple years ago, like another guy recommended...Zweed,

so under the worst conditions, it still gives me a 20f drop over the coil...input to output....

but in all honesty, the convertible top air leaks so badly NO a/c can keep up....that's what I get for going cheep off ebay...shame really as it LOOKS just grand, nice made, whole lot....just don't FIT the install....

:suicide:

 

[gr8vet]

I changed to 134A recently. My mechanic changed the cycling switch. The 134A requires a different switch to allow for 134A operating pressures. My A/C is very cold.

I got the switch from O'Reilly. PN 36674 Cycling switch.

1982 C-3. Mostly stock with damn cold air.

Good deal, thanks for the part number. I will pick up today since I am going by the Zone anyway. thanks

 

[gr8vet]

Hey guys, thanks all for info. This is where I wound up.

I added 1 can of r134a. My low side pressure is at 45psi. Not sure where the high side is, gotta figure out who borrowed my dang gauges and have not returned them! I opened up the recirc vent at floor (i am a looser), sealed off the upper vent very well with some fiber insulation. With windows up, idling for 10 minutes I am seeing 46 degrees at vents. 69 degrees at input of compressor. 130 at exit of compressor, this is with an ambient temp this morning of 93. Large shop fan blowing in front of car, but nothing like really moving down road.
I will definitely check on the cycling switch, and I believe as I roll down the road it will be much much better. Thanks again you guys! Ya'll are great!
tt
Oh, the wife says thanks too!

 

[Geoff Coenen]

i've seen the core of the evaporator so clogged that it looked like a bee hiuve honeycomb - virtually all blocked for air passage - thus no cool temp transfer to the air charge.
You could not blow thru it with compressed air. Sticky, gooey, messy stuff. Just like that bug protoplasm when it smashes on the windshield. Tuff stuff to remove.

Protoplasm: in another life I taught Biology & Chemistry.

 

[gr8vet]

i've seen the core of the evaporator so clogged that it looked like a bee hiuve honeycomb - virtually all blocked for air passage - thus no cool temp transfer to the air charge.
You could not blow thru it with compressed air. Sticky, gooey, messy stuff. Just like that bug protoplasm when it smashes on the windshield. Tuff stuff to remove.

Protoplasm: in another life I taught Biology & Chemistry.

That was funny, thanks for the laugh this morning! tt BTW, what is bird poop made of, sometimes I have had to wet sand it off. Someone should make paint or glue out of the stuff!

 

[DWncchs]

i've seen the core of the evaporator so clogged that it looked like a bee hiuve honeycomb - virtually all blocked for air passage - thus no cool temp transfer to the air charge.
You could not blow thru it with compressed air. Sticky, gooey, messy stuff. Just like that bug protoplasm when it smashes on the windshield. Tuff stuff to remove.

Protoplasm: in another life I taught Biology & Chemistry.

Be glad you didn't run into pureed fish guts poured into the cowl area , that can be a "game over" depending on how sensitive a persons nose is. :cussing: