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1970 Deville - POA valve frosty when heat is on - Pics added

Started by chrisntam, January 17, 2015, 01:23:15 PM

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chrisntam

Took the car out for a drive this morning, had to turn the heat on.  Heat is operating fine, I popped the hood and found the poa valve very frosty  as was the suction side aluminum tubing coming out from the compressor - not sure if frozen or not.  I understand on the '70 model the compressor runs all the time (heat/ac) unless in the off position.  I can't really tell if the a/c is working right as its about 55 to 60 degrees here today.

R-12 system (Dichlorodifluoromethane).

So should the POA valve be frosty w/ the heat on in the winter?  Or is that an indication of a problem w/ the a/c system (low on Freon or blockage)?

Rebuilt compressor, new valves, new evaporator, flushed condenser - all just completed in march/april of 2014.
 
It's always something............
1970 Deville Convertible 
Dallas, Texas

Dave Shepherd

I do not believe the comp. runs all the time, on defrost yes, never saw it on in the heat only position.

jsanford

Yes, the compressor runs all the time with this system. I think frosting of the valve is normal, especially with low ambient temps.

Jeremy
Jeremy
Sacramento, CA
1980 Seville
1981 Eldorado
2016 ELR

Glen

I agree with Jeremy, the AC runs all the time except when the system is in max heat.  The power servo controls that. 
Glen Houlton CLC #727 
CLCMRC benefactor #104

Scot Minesinger

The same thing happened to me a few weeks ago on my 1970 Cadillac.  Usually I do not open the hood right after a drive, and so first time in a while opened hood after a cold weather drive and my POA was frosty too (opened it to check power brake booster).  I reasoned that since the system had remained in same state of refrigeration charge for some time now it was normal, although I do not know for sure.  My system is converted to r134.  At the time with brake problems had bigger fish to fry.  My brakes are fixed.  You can always operate the heat in economy (or vent) where compressor will not operate. 

The rain is coming down major today and next week is supposed to be in the 50's.  Good bye salt on roads and hello to driving my 1970 Caddy next week!   
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

76eldo

That's why we used to unplug the compressor back in the days when these were everyday cars.

Unplug it in November, plug it back in in April, although I personally don't remember the AC compressor running on heat, only AC and defrost.  But I could be wrong...

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

Scot Minesinger

Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

cadillacmike68

In this era, there is an ambient switch that prevents the compressor field coil from engaging when it is 32 deg F  or below outside. Otherwise the compressor will run at all settings other than Vent or Off, primarily to dehumidify the air. Notice how your windows never fog up in a Cadillac when you have the climate control on?   :D

Later years had an econ mode which did not use the compressor, and they shut it off at 40 deg F or below, not 32.

Unplugging it is Ok (I used to do it up north in my 1970), but turn it on every month or so.  Don't want things to seize up from non-use.
Regards,
"Cadillac" Mike

"Cadillac Kid" Greg Surfas 15364

Chris,
I am assuming you are running R-12 in your system.  If so frost on the POA when under light cooling load is normal.  If under a full load you have frost it is an indication of either a shortage of charge or a malfunction.  If you are running R-134a, frost  starts to appear at an earlier stage (of diminishing load)>
For you guys that unplug your compressors, please be prepared to replace the charge and the compressor seals when you finally reconnect the clutch wire.  If the compressor is not run frequently, the seal dries out and leaks.  "In the old days" this was not a problem, because R-12 was $0.39 per can, and a leaking system was acceptable.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

chrisntam

I looked at it again today, it is iced up.  I'll upload some pics later today.

Mid 60s here in Dallas today, top down, nice to get out!

chris.
1970 Deville Convertible 
Dallas, Texas

Scot Minesinger

Chris,

You never wrote if it was r12 or r134.  I'm running r134.  My system is off 75% of the time because top is down.  If it is below say 60'F then I put the heat on thru auto setting.  Mine was frosted up on a sunny 40'F day with top up and heat on.  I do not store my car here in VA where today it is rainy and 40'F.  Tomorrow it is supposed to be 45'F and sunny with salt washed off roads by today's rain.  Will give it a drive and see tomorrow.  As Greg reports this is normal, which is what I thought, as this system has been functioning for 5 years now on the same r134 charge consistently from one year to the next. 
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Jeff Rosansky CLC #28373

#11
Mine does it too.  You are fine.

Ford did that back in the 70's too. I had a 72 Mercury Montego and the a/c ran all the time when the lever was in "Panel."  There was a temp sensor in the grill just in front of the radiator. It was supposed to shut the compressor off when the temp was low.  Well, mine didn't work. The temp lever also had broken loose at the cable mount behind the glovebox.  Now that I think about it, maybe it wasn't all that impressive to the "Ladies" while being out on a date. 
Do you think that when she says "I'm cold" and you say OK, then pull over to the side of the road, open the hood to unplug the compressor, then get back in the car, open the glovebox door to manually move the lever to heat (I had removed the glovebox for easier access) may have been why I didn't have many second dates??
Hummmmm???
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

chrisntam

1970 Deville Convertible 
Dallas, Texas

"Cadillac Kid" Greg Surfas 15364

Chris,
If your site glass is full, it sounds normal to me.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Jon S

Quote from: cadillacmike68 on January 18, 2015, 01:02:54 PM
In this era, there is an ambient switch that prevents the compressor field coil from engaging when it is 32 deg F  or below outside. Otherwise the compressor will run at all settings other than Vent or Off, primarily to dehumidify the air. Notice how your windows never fog up in a Cadillac when you have the climate control on?   :D

Later years had an econ mode which did not use the compressor, and they shut it off at 40 deg F or below, not 32.

Unplugging it is Ok (I used to do it up north in my 1970), but turn it on every month or so.  Don't want things to seize up from non-use.

My 1973 Lincoln (which used a GM Frigidaire system inclusive of C6 compressor) has an ambient temperature mounted in front of the radiator.  The concept of the AC running in the winter was to dehumidify the windshield especially in defrost mode.  Also, it is good to run the AC in the winter to keep the O rings and other seals lubricated.  The ambient switch only kicked in to prevent the compressor from running in extremely cold conditions.
Jon

1958 Cadillac Sedan De Ville
1973 Lincoln Continental Coupe
1981 Corvette
2004 Mustang GT

chrisntam

Quote from: "Cadillac Kid"  Greg Surfas 15364 on January 18, 2015, 06:44:25 PM
Chris,
If your site glass is full, it sounds normal to me.
Greg Surfas

I'll have a look at the site glass, likely next weekend.   Didn't think about it.   :-[   With the added pics, those little bubbles on the line were frozen globules of water/ice.
1970 Deville Convertible 
Dallas, Texas