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A/C guys: Please comment on my recent A/C top off numbers. About right for this car?
Posted by: rnch ()
Date: June 09, 2018 05:56AM

'65 Monza convertible, factory A/C, recent quiet, rumble-free Sanden compressor, '66 style firewall condenser, R-134A refrigerant, two electric cooling fans on the firewall condenser. I am guessing still the factory R11 expansion valve.

These numbers are from an 80 degree/80% humidity morning top off:

High side 235, low side 19.

Center vent temperature, at curb idle: 49 with fan blower on high speed setting, 42 on low speed setting.

Driving at 30 to 40 mph give a center vent temperature of 48 to 50.

The top off was done by a patient, knowledgeable, trusted A/C mechanic with over 40 years of experience in getting the best trade off on internal equipment pressure and coldest air temperature.

I realize a a convertible, with only a thin, non insulated top won't get as cold inside as a well insulated/weatherstripped coupe or sedan will.



Edited 1 time(s). Last edit at 06/09/2018 06:00AM by rnch.

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Re: A/C guys: Please comment on my recent A/C top off numbers. About right for this car?
Posted by: VegasVair ()
Date: June 09, 2018 08:54AM

One issue that will keep you from getting best performance is the 50+ years old
condenser style. That design has been obsolete for ages and was never optimized for R-134.

65 Corsa 140/4 A/C convert.
CORSA+Vegas Vairs

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Re: A/C guys: Please comment on my recent A/C top off numbers. About right for this car?
Posted by: dryenko ()
Date: June 09, 2018 10:38AM

Was the system pulled to a 29" Hga vacuum first, before it was filled?

Bob C aka Dryenko
Dobson, NC 27017

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Re: A/C guys: Please comment on my recent A/C top off numbers. About right for this car?
Posted by: cnicol ()
Date: June 09, 2018 11:29AM

Numbers sound right on the money to me, assuming ambient was around 80F and typical NOLA humidity.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: A/C guys: Please comment on my recent A/C top off numbers. About right for this car?
Posted by: rnch ()
Date: June 09, 2018 11:32AM

cnicol Wrote:
-------------------------------------------------------
> Numbers sound right on the money to me, assuming
> ambient was around 80F and typical NOLA humidity.


The temp AND the humidity were both about 80. It was very early in the morning.

The combo of these two wear me out. I can deal with one or the other; but together..... eye popping smiley

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Re: A/C guys: Please comment on my recent A/C top off numbers. About right for this car?
Posted by: Ratt643 ()
Date: June 10, 2018 04:12AM

Rule of thumb I was taught...10% less charge of R134 in a R12 system than the recommended R12 charge. I have a underdash unit in my 66 F100 with a R12 expansion valve, Parallel slyle condensor and Sanden compressor. Blows very cold air. 134 expansion valve in my 64 Monza factory evaporator and new parallel flow concensor in the trunk with Sanden compressor. When I charged it earlier this year, it was above 80
outside and my pressures were 250 and 20-25 at idle. It blows 40 degree air on low at highway speed.


1964 Monza Coupe

Maryville, TN
U.S. 129 The"Tail Of The Dragon"

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Re: A/C guys: Please comment on my recent A/C top off numbers. About right for this car?
Posted by: rnch ()
Date: June 10, 2018 06:18AM

VegasVair Wrote:
-------------------------------------------------------
> One issue that will keep you from getting best
> performance is the 50+ years old
> condenser style. That design has been obsolete
> for ages and was never optimized for R-134.



IF this car turns into a long term keeper (as I suspect it will!); the condenser will eventually be replaced by the newer R-134 one from Clark's.

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