Automotive Air Conditioning Information Forum

Somehow I have missed all the drama until now, tho I did have a few comments. I think this` is an excellent thread on proper diagnosis, and retrograde replacement of parts and the OP should be congratulated . And you can bet the governing viceroys have the best AC of any

Almost forgot: the vacuum issue.

After alot more research I found another manufacturer of vacuum pumps that seemed to be good. Paid 160€ for it.

For anyone looking in Europe: Value V-i120SV.
Has a vacuum gauge directly mounted to the pump with a proper scale (still not accurate like a micron gauge I know, but better than the small vacuum section on gauge sets). Resolution of the gauge is in 20mbar steps.
And it has a solenoid that closes the port when the pump is switched off so no vacuum can bleed off through the pump.

Did the evacuation myself until there was no rise in vacuum after switching off. First time, vacuum went up a little and then stopped. From what I read, that could have been moisture boiling off. When I was finished, the needle did not move a tiny bit, so I considered that to be okay.

At my elevation, the maximum achievable vacuum was 980mbar and the needle almost touched that point on the scale.

Conclusion: the first two pumps were complete garbage.

The pictured vacuum pump appears to be a very high-quality piece and well worth the money. Good work on achieving a vacuum of 980mBar, or 28.9inHg. Given your location above sea level, that's just about the maximum vacuum achievable.

Now that you have a high-quality vacuum pump, don't forget to closely follow the manufacturer's recommended oil-change intervals to achieve the highest possible vacuum each time you use it.

JohnHere wrote: ↑Wed Aug 21, 2024 8:00 am
I've heard about the existence of both R4 piston compressors and the R4 scroll variant, but I've never replaced a piston version with a scroll version. Please let us know how it works out.

So far it works very nice. I drove the car on a 93°F day and while cruising at 45 to 50 mph, vent temps were around 43°F with the blower on setting 2 of 4, outside air. At idle the temp slowly creeps up to 50°F. The new fanclutch definitely does its thing. I can feel the hot air coming up from under the car when I walk around it idling with the AC on and fully warmed up.

These results are still with the OEM tube&fin condenser. As long as it doesn't leak or brake, I won't change it since the AC is working really cold now.

Another thing that is often forgotten: The previous owner installed a new coolant thermostat, but a 160°F version. He propably thought he did something good for the engine. But not only does the engine never reach it's optimal temperature, what I also noticed that the fanclutch almost never fully kicked in. Since the mechanical fan is the only fan the car has, no electric fans, the AC also only gets the airflow from that fan.
I installed the original 195°F thermostat and with this water temperature, the air being drawn through the radiator gets much hotter and the bimetal spring of the fanclutch actually goes on full blast.

I never understood why changing the thermostat would help with anything, especially in a vehicle with fuel injection. If the cooling system does not do the job, a colder thermostat does not help, its just completely open a bit earlier. With my 195°F thermostat, the engine runs perfect on that 93°F day with AC, even at idle, no overheating.

freakyhead94 wrote: ↑Wed Aug 28, 2024 11:59 pm I installed the original 195°F thermostat and with this water temperature, the air being drawn through the radiator gets much hotter and the bimetal spring of the fanclutch actually goes on full blast.

If the cooling system does not do the job, a colder thermostat does not help, its just completely open a bit earlier. With my 195°F thermostat, the engine runs perfect on that 93°F day with AC, even at idle, no overheating.

I run a factory setting 195°F thermostat in my 1988 Mazda truck and my engine runs perfect with AC, even at idle, no overheating, fan clutch as well. And I'm in Arizona where 93°F is the mid-summer LOW, and we can hit 115°F readily - in the shade !

Cusser wrote: ↑Thu Aug 29, 2024 6:51 am
I run a factory setting 195°F thermostat in my 1988 Mazda truck and my engine runs perfect with AC, even at idle, no overheating, fan clutch as well. And I'm in Arizona where 93°F is the mid-summer LOW, and we can hit 115°F readily - in the shade !

Yes the Arizona heat..My uncle lives in Phoenix, I have been there twice and the heat..What instantly comes to my mind is how we were swimming in the pool and after getting out, within a minute I was dry. But I like the dry heat, has always been in the back of my head to move to Arizona, but..not that easy

As an "old" Chevy guy, they should have stuck with the A6 it was a beast. Every car/truck I have ever had with the R4, I had issues with. My 1998 GMC service truck, with the HT6, it's been good to me, and will still freeze you out.

Hey Tim and John, yes I'm still breathing @72.

A little bit of trivia and brief diversion, if I may:

Many years ago during the 1950's, when people used alcohol (not the drinkable kind) in their cooling systems instead of ethylene glycol because the former was a cheaper alternative antifreeze, thermostats had to be changed from the then-standard 190°F units to 160°F units.

The reason for that was the alcohol would quickly boil off at the higher temperature, leaving the engine block without any freeze protection in the winter. However, the alcohol antifreeze would not boil off at the lower temperature.

Of course, very few cars had A/C back in those days, and it was considered a very expensive novelty.

Mr Bill wrote: ↑Thu Aug 29, 2024 8:47 am As an "old" Chevy guy, they should have stuck with the A6 it was a beast. Every car/truck I have ever had with the R4, I had issues with. My 1998 GMC service truck, with the HT6, it's been good to me, and will still freeze you out.

Hey Tim and John, yes I'm still breathing @72.

Probably better than I am at 60. I had spine surgery a little over two months ago. Doing the PT thing now, trying to walk without a pimp skip.

We are rooting for you, Tim, hang in there. Ya gotta give therapy hell.