A/C Not Blowing Cold Only Cool

[caswda]

84 MB 300D
Can someone possibly give me some suggestions. I have replaced the A/C Compressor (New) Dryer (New) Pressure Switch Fan Switch (On Dryer, New) Expansion Valve (New) Flushed the system with FJC and plenty of air Vacuumed for at least 2 hrs. Fresh Mineral Oil (approx 6oz. Total Dryer and Compressor). Unfortunately R-134 Site glass does look as if there is some air but flowing nicely, System does not leak has held full pressure for a month now. I just can not get this thing to blow cold Just cool! Is there an internal switch to the climate control I could be missing? PLEASE HELP!

[compress ignite]

"Remember,Air Flow Across the condenser is Everything!

The only reason we don't ride horses or in carriages any more is so
that the "Angels Breath" (A/C) can be carried around with us!

Assumptions:
1. New O-rings with Nylog all around
2. The Re-Circulation portion of the HVAC is present and Working.
[AKA it's not Sucking in that Oven Enhanced Humidity from
out of doors.]

'Youse gots to remember these W123 s were originally r12 creatures
(And even though they've got the EXCELLENT old style condensers)
You ain't never gonna get r12 cooling out of r134 WITHOUT some
finagling!

Zomeone (I believe it was on this forum) mounted a Parallel Flow
condenser in front of his regular condenser and "Plumbed" the system
so that the regular condenser was just a Pre-Cooler for the PF condenser.

'get holt of an in-expensive kitchen type thermometer and stick it
in your Vent closest to the Evap so that you can address the issue
in a manner that can be compared.

What kind of Low/High pressures @ what Ambient temps are you running?

WhiskeyDan has some excellent directives at the end of this post:

Ac 123

[caswda]

Thanks compress ignite,
YES! The AF is functioning beautifully, It kicks in strong @ approx: 100F. pulling all that nasty hot air away from the condenser. I have replaced the Engine Thermostat also and she runs a cool approx: 82C at norm operating temp and rises only fractionally with the A/C Functioning. She actually dissipates heat rather well considering her age. Which is why I expexted a little better performance from her. Yes all rubber that I saw was replaced. I know, some people do not realize the importance of that.) I will update you with true pressures and temps of the system shortly! Question? If I were to take the time to break it down and start over is it worth it for R12?

[Diseasel300]

Since you used mineral oil, evacuate the system and charge with R12 IMMEDIATELY. R134a requires POE or PAG oil, it is NOT compatible with mineral oil, you'll burn up your compressor in very short order.

Your other option is to evacuate the system, flush again, and refill with PAG or POE and use R134a.

There are many reasons why the A/C may not be blowing very cold. Worn expansion valve, restriction in the system, dirty coils, dirty fan, recirculation flap not functioning, monovalve stuck open....

You also didn't specify how long it takes to cool off. If you start the car and drive away and expect ice cold air, you're in for a disappointment.

[compress ignite]

I missed the Lubricant that was used.

You are correct.

_____________________________________________________________

Caswda,

Since you're looking at breaking it down again to flush for the Mineral Oil...
AND you know what you're doing.
I'd REALLY consider the R12 route especially if the system came out of the 2nd
attempt leak free.
It's a lot of work but 7/8 ths of it is required by the M.O.

[tyl604]

Why did you use R134a? If you can, go back to freon R12.

[compress ignite]

How much Contamination could the R134 have caused to the mineral based oil
in a week or two of running with it ?

The Crazy Irresponsible side of me would want to just REMOVE the R134
Apply Vacuum Overnight and refill with R12.

Or is that asking for an HVAC Train Wreck ?

[vwnate1]

Subscribed .

[Diseasel300]

Originally Posted by compress ignite

How much Contamination could the R134 have caused to the mineral based oil
in a week or two of running with it ?

The Crazy Irresponsible side of me would want to just REMOVE the R134
Apply Vacuum Overnight and refill with R12.

Or is that asking for an HVAC Train Wreck ?

If he is going back with R12, then yes, that should work. If he's sticking with R134a though, he's going to have to flush the system and refill with the correct oil. It's up to the OP.

The oil needs to be compatible with the refrigerant to circulate throughout the system. Mineral oil will not mix or flow with R134a. It will get circulated to the evaporator and sit there, never returning to the compressor. Next thing you know, the compressor grenades and you're back to square one. PAG oil mixes with HFC refrigerants like R134a and POE behaves similarly, this is why you're supposed to flush and refill the system when converting from a CFC to HFC refrigerant.

It wouldn't be as big of a deal with a compressor with a sump like the Nippondenso used in later cars, but with an R4 which already has oil circulation problems, you're asking for big trouble in a short time by not doing the job correctly.

[marco5]

Above posts are point on - you're oil is incorrect for the refrigerant you are using. Have it vacuumed at a shop for 1hour+ and put in proper R12. Cans you buy from auto parts stores labelled R12 are not the real thing.