1972 Air Conditioning

[Dick W.]

Re: 1972 Air Conditioning

Larry,

I did the heater hose test that you suggested: Plugged the Intake Manifold nipple on the engine, and plugged the end of the removed hose. I tried this first to see how much the heater core was messing with my interior temperature readings when the A/C was on.

I also put a box fan in the front of the grille, and one behind the car to pull more air through (and also pull the exhaust gasses outside of my garage!).

Results were similar to before the test: Ambient Temp.= 86 deg. F. Inside Temp. = 56 deg. F. @ 2,000 RPM on MAX A/C at RH vent.

This would seem to indicate that the heater core is not affecting the temperature that much, if at all.

Also, I am getting 30 deg. F. cooler air inside the cockpit. Isn't that about as much as can be expected while keeping the system OEM and with running R-134a?

I could evacuate and try to recharge again, but it seems like a lot of effort for a few degrees of cooling.

Best,

Mike

[Larry M.]

Re: 1972 Air Conditioning

Mike:

You may or may not get the 40 F duct temperatures that Dick is reporting, but you damn sure should be able to get in the low 40's with you system.

Only you can decide if the additional work is worth it...........but I would do it............you have come this far. Four cans of 134a is about $35, and probably 2-3 hours of your time, max, to pull a vacuum and recharge it.

Larry

PS: Maybe just let it be until next week and take some rest now.


PSS: Maybe just fly Dick in to do his magic.

[Michael C.]

Re: 1972 Air Conditioning

Larry and Dickie,

Thanks for your input! I am more optimistic now about my 46-year-old A/C system, and will tackle the recharge this weekend.

I do want to call you Larry, to get your pointers on recharging with cans -- without adding air into the system -- I am sure that's probably what happened when I did the last recharge with cans. You mentioned 75% of R-12 charge, but I read in another forum that it should be 80%... if it is that sensitive as Dick mentioned, I will want some clue as to when to stop charging!

Any particular time good for you this evening after 5:00 PM Central, or tomorrow AM?

Thanks much!

Mike

Mike:


You may or may not get the 40 F duct temperatures that Dick is reporting, but you damn sure should be able to get in the low 40's with you system.

Only you can decide if the additional work is worth it...........but I would do it............you have come this far. Four cans of 134a is about $35, and probably 2-3 hours of your time, max, to pull a vacuum and recharge it.

Larry

PS: Maybe just let it be until next week and take some rest now.


PSS: Maybe just fly Dick in to do his magic.

[Larry M.]

Re: 1972 Air Conditioning

Mike:

Try tomorrow around 9:30 AM. I will hang around the phone at this time, unless you say otherwise. If this is not convenient for you, give me your best time.

Larry

PS: I am fine with 80% charge for R134a. Is your 1972 system capacity for R12 3 lbs 3 oz??? Should be on the compressor decal.

[Michael C.]

Re: 1972 Air Conditioning

Larry,

Thanks for the conversation and the information!

I finished the process within 3 hours, just as you foretold. Good news! I have 44 deg. air blowing in the cockpit! And that is in my hot garage with a couple of measly fans moving air. Ambient air temp was 88 deg.

I can't wait to take it down the highway and see what it is reading when rolling. Apparently I didn't purge all the air from the hoses when charging, which of course was forcing air into the system along with the R-134. I wasn't able to get a completely clear Sight Glass until I started on the 4th can, but after less than a 1/4 of that can was in the system, the glass cleared right up. I put in the recommended 2.6 lbs of R-134a (80% of R-12 capacity which was 3.25 lbs.).

Thanks again for all your help. I can now say that my system is performing as it should -- and it's all OEM stock.

Best Warm Regards,

Mike

[Larry M.]

Re: 1972 Air Conditioning

Mike:

Great news!! Thanks for the feedback.

It was good talking to you this morning. You went thru a lot of effort with this problem over the last week or so, but now you got it fixed. Congratulations.

Larry

[Dick W.]

Re: 1972 Air Conditioning

Mike:

You may or may not get the 40 F duct temperatures that Dick is reporting, but you damn sure should be able to get in the low 40's with you system.

Only you can decide if the additional work is worth it...........but I would do it............you have come this far. Four cans of 134a is about $35, and probably 2-3 hours of your time, max, to pull a vacuum and recharge it.

Larry

PS: Maybe just let it be until next week and take some rest now.


PSS: Maybe just fly Dick in to do his magic.

I think the real magic to Kermit was a new condenser. As they age they get a lot of debris in the lower tubes plus as the exterior ages, it corrodes and some of the fins lose their attachment to the tubes.

My final idea is that get it close with the guages and then do the feel test. Once the suction side of the evaporator "grabs" your hand when you touch it, you have the ideal charge. 55 years of A/C and mobile refrigeration repair and maintenance tends to teach you a few things outside the book of "larning"