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1987 Caprice Vent Temp

ClickHere on Wed July 11, 2012 1:49 PM User is offline

Year: 1987
Make: Chevy
Model: Caprice
Engine Size: 350
Refrigerant Type: R12
Country of Origin: United States

This is my first time posting here, and I couldn't find this answered in the archives.
I recently had my a/c repaired and refilled with virgin R-12. A small amount leaked out when my mechanic was filling it, but he said that it wouldn't affect the output. My vent temperature was measured at 40 degrees, which cools the car down somewhat, but not enough, especially for the back seat passengers. However, I remember the a/c in this car being much stronger several years ago. My condensor, compressor, blower, and dryer are 5 years old and seem to be working fine.
What is the proper (original) vent temperature of a 1987 Chevy Caprice 350 (9C1 Police Package)? Does the 9C1 Police Package hold more R12 than regular Caprices? How can I measure how much refrigerant is in the system?
Also, it takes about a minute for the air to come fully out of the dashboard, instead of the floor (where the heat comes from). What causes this delay? Is it a leaky diaphram or vacuum line?

JJM on Wed July 11, 2012 8:56 PM User is offline

Not showing any difference for the 9C1... and why would there need to be with 56 ounces of penguin killer.

Only accurate way to measure the charge level is to recover the charge and weigh it. But you should be able to get fairly close with regular pressure readings.

The delay in coming out of the vents is likely a leaky actuator, collapsed vacuum lines, plugged vacuum tank, or even something in the control head. Doubt it, but is this vehicle auto climate control?

Joe

When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com


ClickHere on Thu July 12, 2012 12:33 AM User is offline

Thanks, Joe!
I don't have climate control. Until I figured out (less than 3 years ago) exactly which vacuum line was getting crushed, the car used to frequently blow hot air through the vents, after any time that a mechanic looked at the carburetor. I changed some vacuum lines yesterday, but one of them kept the vents blowing heat, so I changed that one back. I may try clamping them.
Do you know what the vent temperature should be with the a/c on, in a 1987 Caprice? The 40 degrees that is blowing out now, doesn't feel as cold as the a/c was several years ago. However, before I ask my mechanic to check if there is enough freon, I want to be sure that I know what temperature it should be. I have some cans of R12, in case it's low.

Jerry

fonebone on Thu July 12, 2012 1:23 AM User is offline

Hi Clickhere; If you have 40 degree at the vents you do Not have a problem!! My 79 Caprice manual calls for 48 to 52 degrees as normal outlet temp. Same basic car as yours(mine's a 2 dr.). I still drive it, it cools a couple degrees cooler because I installed a parallel flow r-134 condenser. I will be very cool after a few miles in mine, no problem. I'd love to see 40 at the vents! I'm guessing yours is a 4 door==Lots of glass for sun to cook the folks in back, big cabin, meaning those in front are cooled, those in back are warmer. That has always been a problem with big interior cars. Now the vacuum leaks- Manual says to check purple hose connector behind glove box, disconnect this and check with vac. gage,must be 10 in. of vac. minimum to pull doors open etc. If not, go under hood check the black vac. ball on cowl for cracks,etc, then the line to intake man. The line running from inside cab to engine bay is (should be) a thin brown plastic, easily broken line hard to see on pass.side. Must be in good shape. Replace if you have to with thin rubber tubing. By the way-my vents start blowing in under 10 seconds. Report back with what you find, OK?

ClickHere on Thu July 12, 2012 11:22 AM User is offline

Thanks, Fonebone!
I do have a 4 door, since mine is an ex-cop car. I bought the car when I was in school, over 20 years ago. It used to blow ice cold air, until a mechanic tampered with the ac, and broke the whole system. After a few years of no ac, I had another mechanic fix it, which involved replacing most of the hardware. He had only R134a, which didn't cool it much, even on the day that he finished the work. Now that I have kids, I switched back to R12, which is definitely better than the R134a, but not as good as it was before the first mechanic broke the system. I would like to bring it back to the way that it originally was, so that my young kids aren't sweltering hot when the temperature is 95 degrees.
This weekend, I am going to try to look at what you suggested.

Jerry

ClickHere on Thu July 12, 2012 2:29 PM User is offline

One other thing that I was wondering: I read that, when switching back from R134a to R12, you should change the dryer. My mechanic said that changing just the filter is enough. Is he right? If not, what happens if it isn't changed?

Jerry

fonebone on Fri July 13, 2012 1:01 AM User is offline

You did the right thing going back to r-12! Did you use the original drier when you converted over to r-134 and just put in r-134? That is a recipe for failure. Oil is different for the r-12 and r-134. Never mix the two. Not sure what your mechanic means when he says do not change the dryer, just the filter. The drier is a sealed , non serviceable can containing a filter and drier, unless he put an inline filter in the system. When you had it converted back the entire system should have been flushed properly to rid it of all oil and junk. Then mineral oil(for r-12) added.

ClickHere on Fri July 13, 2012 6:18 PM User is offline

The R-12 was vastly superior to the R134a. Even now, when it isn't blowing as cold as it did in the 1990's, it still is much better than it was with the R134a. I just want to restore it to how it used to be, especially since my system is mostly 5 years old or less.
When it was converted to R134a in 2007, the mechanic changed the dryer, compressor, and condenser, and maybe some other things. It cost a fortune. When I converted it back a couple of weeks ago, the mechanic (not the same one from 2007), changed an inline filter in the dryer, but not the dryer itself. He vacuumed the system dry, and changed the a/c oil. He seemed to do everything the way that I read to do it, except for 1) not changing the dryer and 2) a little R-12 leaked because his adapter/hose was no good. I am wondering if the lost freon is enough to keep the temperature noticeably warmer than it used to be. I never measured the vent temp before the 1999 mechanic broke the system.

fonebone on Sat July 14, 2012 10:16 PM User is offline

One thing I forgot to mention was that GM vacuum operated coolant shutoff valves , at the intake man., are notoriously bad leaker's , and will allow hot coolant to go into the heater core when you have it in a\c mode, especially with less vacuum in the lines. I finally put a cable (underdash) operated manual in-line (small hose)shut off valve that positively stops all hot water from going into the core. This is also where you need full vacuum in the hoses to operate correctly. Feel your hoses when your car is up to temp-there should be no heat in either inlet (smaller) or outlet of the heater hoses when in a\c mode. Any hot coolant going in WILL increase vent temps. Too bad you didn't record vent temps from before-only way to compare.

2005Equinox on Sun July 15, 2012 1:55 AM User is offline

I replaced the coolant shut off valve in my 1985 Caprice last year and I have noticed a difference in A/C performance. Mine is able at least according to the thermometer I have to keep a vent temp of about 38-42 degrees on Max and medium high fan in normal conditions. Mine has R-134 and all origional components other than the compressor. My system overall works pretty well unless it is extremely hot or if you are idling for too long. The same system in the 1981 Pontiac Bonneville still works a little better and that one doesnt lose as much cooling ability at idle. That one runs about 36-40 or so degrees in the same conditions as I listed before.

-------------------------
2008 Chevrolet Impala LS
1981 Pontiac Bonneville


2007 Sears Craftsman Lawn Tractor


1985 Chevrolet Caprice


1986 John Deere 165 lawn tractor

2005Equinox on Sun July 15, 2012 1:58 AM User is offline

Sometimes on both cars I wish I could fit the A-6 compressor instead of having to use the R4 one. But you cant.

-------------------------
2008 Chevrolet Impala LS
1981 Pontiac Bonneville


2007 Sears Craftsman Lawn Tractor


1985 Chevrolet Caprice


1986 John Deere 165 lawn tractor

fonebone on Sun July 15, 2012 4:39 PM User is offline

One thing you mentioned--gets warmer at idle- you did not mention that the fan clutch had ever been replaced. This is a must if over 2,3 years old. Normally, the factory fan clutch is a thermal clutch, where the thermo switch at the clutch senses hotter temps then locks up the fan for more flow across the condenser. They will wear out and slip and not cool as it should, yet you think it's ok 'cause it's noisy. I finally replaced my thermo clutch during the hot weather with a "non-thermal" fan clutch that stays locked up from idle till about 50 or so mph where it then starts slipping. Sure, it's a bit noisier, but it really pulls the air across the condenser and you feel the vent temps drop. You should try one.

ClickHere on Sun July 15, 2012 4:56 PM User is offline

I'm worried that, if I shut off flow to the heater core, I run a greater risk of overheating. I often drive in stop-and-go (bumper-to-bumper) traffic. Do I need to be concerned about that?
I am going to check the stuff that you mentioned earlier. If I don't find them or can't tell if they are a problem, I am going to bring the car to the mechanic next weekend.

Jerry

fonebone on Sun July 15, 2012 5:15 PM User is offline

That's a trick when you were racing a stock car, and to keep from overheating you threw the heater fan on high- also applies today, if you have a temp gage in your car, you are in traffic, and you notice temps climbing a bit higher than normal, throwing the heat on full might help till you can pull over safely. Any car with a radiator in GOOD shape (and no blockage) will dissipate heat with no problem. The heater is just that--a heater for cold weather. ( or to blend in a small amount of heat when the a/c, even at it's lowest setting, can get too cold, as on a long trip when the cabin is cooled down. humidity has been removed, and the lowest blower speed is still too chilly. Any well maintained, and I might add, well designed system, is capable of doing that.

Edited: Sun July 15, 2012 at 5:15 PM by fonebone

ClickHere on Mon July 16, 2012 12:34 AM User is offline

Although I rarely overheat, I used to use the heater to cool the engine down: after a long trip, I popped the hood, put the transmission in neutral, and ran the heater to cool down the car. If my car overheats, I do the same thing, but also step lightly on the gas. The car usually cools down quickly. I wish that I had gauges, but my car came with idiot lights. I'm tempted to install gauges and convert my gas gauge to digital, but haven't yet.
I check some of the things that you suggested earlier, and made sure that the connections are tight.
If my mechanic can't get the vent temp lower, I may put a shut off valve on the heater core. Unfortunately, this week, it's supposed to hit 97 degrees.

Jerry

2005Equinox on Wed July 18, 2012 1:33 AM User is offline

Shutting off flow to the heater core isnt any different than moving the heater control to cold. Right?

-------------------------
2008 Chevrolet Impala LS
1981 Pontiac Bonneville


2007 Sears Craftsman Lawn Tractor


1985 Chevrolet Caprice


1986 John Deere 165 lawn tractor

ClickHere on Wed July 18, 2012 8:05 PM User is offline

I think that it is different. Setting the temperature to cold means that the heater core still has coolant flowing through it, and is still cooling it, but the airflow is not directed towards the passengers. I hate that the Caprice is designed so that, in the absence of vacuum, it defaults to full heat. I wish that it defaulted to nothing (untreated outside air).

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