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Colder AC.

4K views 25 replies 13 participants last post by  161qv 
#1 ·
My AC works good. But not as cold as I would like. I was wondering if there is anything I can do. A better condenser perhaps? I have a heater hose shut off, new exp valve, drier and air mix door on fully cold. If the car is moving it cools better, hence the condenser idea. Any thoughts?
 
#2 ·
Running the radiator cooling fan on high speed by switching brown and brown-white wires at radiator thermal switch connector in the summer helps. Be sure to keep recirculation door stays closed when button pushed and green light on.

Be sure expansion valve pig tail sensor tube(s) insulated as well as tubing from evaporator to PDI valve on inner fender well with monkey poop a/c sealing tape..

Be sure round outlet/inlet coupling between evaporator box and blower motor sealed well.

And of course proper amount of R134a in system.

Good seal on top of false firewall and bottom of hood, too.

I added a 12 oz can of R134a to daughter's 164L today to get low side to run at about 30-32 psi and high side about 225psi.
 
#3 ·
Be sure round outlet/inlet coupling between evaporator box and blower motor sealed well.
That is critical. The factory foam seal is useless, especially with age. It is porous and sucks hot air from around the engine. You need to pull the evaporator and blower out and make a new donut out of high density foam. Also seal the units where they meet the firewall with the same sort of foam but thinner. You can get it with a sticky backing. These systems will never work efficiently with the old sealing stuff in them. They are actually quite a heavy duty system but were compromised from new by the rubbish sealing material. Believe me it makes a huge difference. It is also important to use the correct expansion valve in the evaporator. The generic Chinese ones don't work. Alfissimo sells the proper ones. If your factory one is working leave it on there.
 
#10 ·
Click on John's link in his post (#7). In that thread, click on the 3b link at the bottom of John's post #1. It will take you to the Guide. Scroll down to page 10 where John talks about the condensor and mentions he got it at Nostalgic Air.
 
#12 ·
Steve. In post #2 you say low 30-32 and high 225.

1993 164L. When I initially start the car the pressures climb to 32/225, then the engine cooling fan comes on and the pressures drop 25/150. Eventually, as the car runs for awhile, the engine cooling fan remains on constantly (the engine is not overheating, I think the pressure switch is keeping the fan on) and the pressures remain steady at 31/160.

So, when you say 30-32/225, is your engine cooling fan cycling or is it on constantly?
 
#13 · (Edited)
Cooling fan will come on about 215psi high side and cut back off at about 150psi high side. If stock wiring set up and cooling fan running on low speed with a/c on you may not be able to get high side back to 150 so fan will stay on.

It is this way on my 164S but on my 164L I have switched brown and brown-white wires at radiator thermal switch connector so cooling fan runs on high with a/c on and will cool better and bring high side pressure back down to 150 and cut off fan until pressure builds back up to 215+.

Cooling fan will also run on high speed this way when radiator low speed 198F switch cuts on and engine runs cooler in the summer.

I need to switch those two wires on my 164S, too.
 
#14 · (Edited)
I am working on new and better condensers. Made in Italy, very nice unit. I also have PF units if needed. I recommend as well to use resistor and original or lower temp fan switch. Hook up according factory setup. I have never had issues and I have nice cool temps even in hell (phoenix). I am thinking of possibly adding a pusher fan, similar to my audi which has 3 fans. Slim enough to add more air.





 
#15 ·
"Good seal on top of false firewall and bottom of hood, too."

How, Steve? Just re-install the plastic cover, or is there something else we can do?
Also, do you have any current photos of everything you monkey pooped?
My new compressor (along with the new receiver/dryer, condenser, R-134 hoses, and expansion valve) and fan are working properly, but not cooling very well in the high 90, humid Texas heat.
Lastly, in the tradeoff between setting the serpentine belt tension too tight versus too lose (to save the water pump), can a loose belt lead to poor AC performance?
 
#16 ·
If the belt isn't squealing, it's likely not to loose. There's a rubber seal that runs along the top of the false fire wall. It often collapses, not making a good seal. Go to Lowes or Home Depot and buy a length of concrete expansion joint. It's grey and round. I can't remember what size I used, but like 3/4 ". Feed it through the center of the rubber seal on the false fire wall to fluff it up and get a better seal. Check either end of the rubber seal also to make sure there aren't any gaps between it and the fender.
 
#17 · (Edited)
Curt - The 90s and high humidity is pretty tough on an A/C. I found it took a day or two for the system to settle-in after full charge and provide the best cooling. I also found that it takes more on the order of 40-43 oz of R134 rather than the conventional wisdom of 36oz as a replacement for the R12.

What kind of temperature drop are you getting across the evaporator (ambient vs. vent temp)? What are the low and high side pressure values? Mine settle in at about 30-32 and cycling between 160 and 220 on the high side standing still at idle, depending on what the fan is doing.

I have my accessory belt set at about 65lb tension vs. the, I think, 125lb tension spec. I think that's ridiculously high and very hard on bearings. No issues at 65lb.
 
#19 ·
If you got it use it from PDI valve on inner fender well to false firewall and around expansion valve pig tails.

I never thought about using is on hose going to condenser by radiator. I guess home depot foam pipe insulation maybe a better choice there.
 
#20 ·
Just to update, I had not re-installed the plastic cover over the false firewall, but after re-installing the plastic cover (I have great seals and rubber all over this 77,000 mile car), tightening the belt, and topping off the AC, I'm getting as cold air as I can probably get here in Texas, about 60 degrees/sometimes cooler at the center dash, about a 30 degree drop.
And it seems that with my stepper motors not working properly, I'm getting cool air blowing on my knee and out the center dash..
 
#24 ·
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