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Posted: 7/11/2010 7:40:11 AM EDT
I have an old 1965 coronet convertible.
A long time ago I installed the classic auto air system and it worked fine.

A couple years back, I swapped motors and ac compressors but only recently got to recharge the system.

So now it is running mostly the classic auto system, but running a 2000 durango 5.9 ac compressor.

We charged the system till the sight glass showed no foam or bubbles and it seem to blow cold. about a 20 degree difference in temp.
And it seems to blow cold when driving surface streets. But when I hit the high way, it blows warm air.

I think it is because it is over charge, but not positive. The reason I say that, is the symptoms are oposite an under charge. low rpm would be hot and high rpm's would be cold.
The heater valve is electric so it isn't moving due to rpm and the blend doors are also electric.
No engine temp issues at any speed.
Link Posted: 7/11/2010 12:07:18 PM EDT
[#1]
Quoted:
I have an old 1965 coronet convertible.
A long time ago I installed the classic auto air system and it worked fine.

A couple years back, I swapped motors and ac compressors but only recently got to recharge the system.

So now it is running mostly the classic auto system, but running a 2000 durango 5.9 ac compressor.

We charged the system till the sight glass showed no foam or bubbles and it seem to blow cold. about a 20 degree difference in temp.
And it seems to blow cold when driving surface streets. But when I hit the high way, it blows warm air.

I think it is because it is over charge, but not positive. The reason I say that, is the symptoms are oposite an under charge. low rpm would be hot and high rpm's would be cold.
The heater valve is electric so it isn't moving due to rpm and the blend doors are also electric.
No engine temp issues at any speed.


Did you charge with R-12 or R-134a?

The sight glass is meant for R-12, if you charged with R-134a until you had no bubbles, your are way overcharged.
Link Posted: 7/11/2010 12:22:17 PM EDT
[#2]
r 134a.

Was doing the charging at shop, and the mechanic there(buddy works there and we used their charging equipment) seemed to think there should be no bubbles as well.
The system is a r134 system.

Interesting though, I thought that 80 percent was for original r12 systems. I will be giving classic a call in the morning, anyway, just looking for other feed back. Thanks.
Link Posted: 7/11/2010 12:58:26 PM EDT
[#3]
With a sight glass on 134 you will generally have bubbles at idle but they go away if you rev it to 1500 rpm's or so. They are generally not used to charge 134a.

Any idea how much R134a was installed, or what the pressures were? 20 degree drop at the vents is poor cooling, unless it is 70 degrees out.

If you don't have a system capacity the general way to charge R-134a is with hi/low side pressures, and temp on the inlet and outlet of the condenser, I don't bother looking at the sight glass even if it has one.
Link Posted: 7/11/2010 2:09:31 PM EDT
[#4]
we put in 2.2 pounds.
maybe 2.3.

Pressures we around 200 hi, and around 40 low if I recall correctly.
The high is going to be off since it is electric fans, and I put a trinary switch in the system. Fans come on at 250 shut off at 200.

it was about 70 degree out put. to 73. When I reved it it went to 77.
Link Posted: 7/12/2010 6:31:45 AM EDT
[#5]
Just got off the phone with classic.
WAY over charged.
only requires 24 oz, I have like 35 oz in it.
you were right, no way the sight glass should be clear. They tape over it so people don't use it.

Lol, I pulled the tape because I figred they covered it from spray bombing and forgot to remove the tape.
Link Posted: 7/21/2010 11:38:07 AM EDT
[#6]
Quoted:
Just got off the phone with classic.
WAY over charged.
only requires 24 oz, I have like 35 oz in it.
you were right, no way the sight glass should be clear. They tape over it so people don't use it.

Lol, I pulled the tape because I figred they covered it from spray bombing and forgot to remove the tape.


I removed the tape too.  Learn something every day.  I didn't pay attention to bubbles, though.  Get a decent set of gauges.  20 degree temperature shift is not very good.  Hopefully that corrects when you recharge.  Did you vacuum purge it first?
Link Posted: 7/22/2010 12:18:07 PM EDT
[#7]
used a machine at my buddy's shop. He works for the mercedes dealer.

It did cool down more. But apparently all these years I put the heater valve in wrong, so I will have to deal with that next weekend.
Think I got closer to a 30 degree change. Was pushing about 65 out the vents, but apparently the heater was kicking in.
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