A/C Performance Erratic - Chevy Impala SS Forum
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post #1 of 11 (permalink) Old 07-18-2018, 07:16 AM Thread Starter
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A/C Performance Erratic

Had my A/C recharged a couple weeks ago. The shop pulled a vacuum on it for an hour and it held. The coldest it gets is about 40F, but sometimes it won't go below 60F. I haven't been able to correlate any certain driving behaviors such as city stop and go vs highway to this. Radiator and condenser are free of debris. I and thinking of spraying the evaporator (with evap in car) with coil cleaner. Any coil cleaner brands recommended? One with a hose would be best.

1994 Caprice Wagon-3.42|Impala SS Wheels/9C1 Wheels|Centrix Rotors|Fleetwood J55 Calipers|Koni Fronts, Monroe SS Rear|Bonneville 6 ways|Z28 Cluster|Pypes X-pipe|Dynomax Super Turbo's|[email protected]
1991 OCC|'93 Z28 LT1| ZZ4 Cam|SLP TC|Home Depot CAI - SOLD|[email protected]??
1983 Camaro Z28-I bought it new|5 speed|350 4 bolt|'90 Corvette heads, SLP headers and 3" exhaust|Konis|4 wheel discs|3.73. SOLD
2002 Regal GS|XP Comp Cam|SLP headers|3" downpipe|3.3 pulley|[email protected] (traction limited) SOLD


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post #2 of 11 (permalink) Old 07-18-2018, 09:17 AM
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What selector mode of the A/C are you using?

I always start with the traditional "AC" & full blower motor setting mode when the car is hot, and eventually switch to the "MAX" setting after about 4-5 minutes, where it recirculates the cabin air. and drop the blower motor to the 3rd highest setting.

When I have the AC set on MAX mode, and the blower on full, the temperature will only go down to ~60'. Once I drop the blower to the 3rd highest setting, I'll get the temperature down to ~36-38' out of the RH vent.

Also the vent temperatures will not stay in the 30s when at idle. When I'm in traffic, I typically see the temperature rise a little above 50'. Once the compressor is spinning a little faster the temperature drops.

Clear Image Tri-Ys & Hi-Flow cats >> 2.5" X-Pipe & Magnaflow Tri-Chambers, Mike Harris 4L60E, Circle-D 2,400 RPM TC, All MOOG FT End & Del-A-Lum bushed MOOG CTRL Arms, Eibach FT & New Stock HT rear springs. Hotchkis Sway Bars & End Links, RAISS, 3.73 Gears in Eaton carrier, Dynoshaft & CIA Loop, BMR Trailing Arms, Braided Brake Hoses, Taylor Spiro-Pro Wires, AutoMeter Water Temp & Oil PSI Gauges, Impala Console. ATE Blue Brake Fluid. Skip White distributor. 20's, Z28 Cluster, Corbeau GTS Seat
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post #3 of 11 (permalink) Old 07-18-2018, 11:52 AM Thread Starter
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Junior,
Like you, I start with the blower on third position (not Max) and switch to Max a few minutes later. But I usually keep it at that setting.

At present, the 1st-3rd blower settings run the blower, but don't seem to move much air. I have a new AC Delco blower motor resistor on the way and maybe that will allow me to use the lower setting. I have been using the middle vents to measure temp, so I will check at the right vent.

Also, I just installed one of my older wagon specific blower motors that I forgot I had and it really does move some air as compared to the aftermarket ones. A few drops of oil on the bottom and it seems as good as new.



Thanks for the assistance. I will keep track of what happens and reply back here.

1994 Caprice Wagon-3.42|Impala SS Wheels/9C1 Wheels|Centrix Rotors|Fleetwood J55 Calipers|Koni Fronts, Monroe SS Rear|Bonneville 6 ways|Z28 Cluster|Pypes X-pipe|Dynomax Super Turbo's|[email protected]
1991 OCC|'93 Z28 LT1| ZZ4 Cam|SLP TC|Home Depot CAI - SOLD|[email protected]??
1983 Camaro Z28-I bought it new|5 speed|350 4 bolt|'90 Corvette heads, SLP headers and 3" exhaust|Konis|4 wheel discs|3.73. SOLD
2002 Regal GS|XP Comp Cam|SLP headers|3" downpipe|3.3 pulley|[email protected] (traction limited) SOLD


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post #4 of 11 (permalink) Old 07-18-2018, 12:01 PM
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Quote:
Originally Posted by Fullmoonboogie2002 View Post
Junior,
Like you, I start with the blower on third position (not Max) and switch to Max a few minutes later. But I usually keep it at that setting.
I see your in Indy, so not as hot as me in Tejas, but I'm sure you still get to the 90s and have humidity. Once you get the cabin somewhat cool, switch to the MAX setting so you will recirculate the cold air and the system won't have to work as hard cooling and removing humidity.

Quote:
Originally Posted by Fullmoonboogie2002 View Post
At present, the 1st-3rd blower settings run the blower, but don't seem to move much air. I have a new AC Delco blower motor resistor on the way and maybe that will allow me to use the lower setting. I have been using the middle vents to measure temp, so I will check at the right vent.
That's been a thorn in my side for a while. I don't think the 2nd & 3rd settings are appropriate. They need to have the blower motor moving faster, as there is such a BIG difference in speeds between 4th and 3rd, and then 2nd. I haven't fiddled around with trying to play with the resistor pack on the back side, but maybe some day when I have completed everything else I'd like to do I can play with that with some help from the EEs I work with.

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Originally Posted by Fullmoonboogie2002 View Post
Also, I just installed one of my older wagon specific blower motors that I forgot I had and it really does move some air as compared to the aftermarket ones. A few drops of oil on the bottom and it seems as good as new.
That's right, I posted a few pix a while back to another thread concerning the differences between two blower motors, as it has been discussed here. The squirrel cage on the OEM motor was taller and moved more air.

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Thanks for the assistance. I will keep track of what happens and reply back here.
No problem. Just be glad you're not hitting the 100s like I will be for the next few weeks!

Clear Image Tri-Ys & Hi-Flow cats >> 2.5" X-Pipe & Magnaflow Tri-Chambers, Mike Harris 4L60E, Circle-D 2,400 RPM TC, All MOOG FT End & Del-A-Lum bushed MOOG CTRL Arms, Eibach FT & New Stock HT rear springs. Hotchkis Sway Bars & End Links, RAISS, 3.73 Gears in Eaton carrier, Dynoshaft & CIA Loop, BMR Trailing Arms, Braided Brake Hoses, Taylor Spiro-Pro Wires, AutoMeter Water Temp & Oil PSI Gauges, Impala Console. ATE Blue Brake Fluid. Skip White distributor. 20's, Z28 Cluster, Corbeau GTS Seat
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post #5 of 11 (permalink) Old 07-18-2018, 03:29 PM
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so this is a 1994 vehicle ??? if so then when made it used R12 not R134..

R12 has different coils .. so when it was converted to R134 the ac will not work as good as R12 would. its about the evap coils .. when high humidity the R12 coils will not clear off the water ..less air cooling..

other causes compressor clutch slipping, replace the old low pressure switch,measure the pressures low and high @1200 rpm with all doors open and blow at the max ...air temp 80F .. low should be 40 psi high should be about 275 -300 psi..since a R12 system as designed high pressures may be a little over 300psi..

pressure testing can reveal air in system too much / too little refrigerant ..
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post #6 of 11 (permalink) Old 07-18-2018, 03:48 PM
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Quote:
Originally Posted by Fullmoonboogie2002 View Post

[SNIP]

Junior,
Like you, I start with the blower on third position (not Max) and switch to Max a few minutes later. But I usually keep it at that setting.

At present, the 1st-3rd blower settings run the blower, but don't seem to move much air. I have a new AC Delco blower motor resistor on the way and maybe that will allow me to use the lower setting. I have been using the middle vents to measure temp, so I will check at the right vent.
As a note, I wasn't as specific as possible earlier..........

I have my Snap-On thermometer in the right-center vent, not the far right one. Also, I also close the far right/passenger's vent when I'm the only one in the car. Not that it's relate to the vent/cabin temperature but thought I'd mention it.

Clear Image Tri-Ys & Hi-Flow cats >> 2.5" X-Pipe & Magnaflow Tri-Chambers, Mike Harris 4L60E, Circle-D 2,400 RPM TC, All MOOG FT End & Del-A-Lum bushed MOOG CTRL Arms, Eibach FT & New Stock HT rear springs. Hotchkis Sway Bars & End Links, RAISS, 3.73 Gears in Eaton carrier, Dynoshaft & CIA Loop, BMR Trailing Arms, Braided Brake Hoses, Taylor Spiro-Pro Wires, AutoMeter Water Temp & Oil PSI Gauges, Impala Console. ATE Blue Brake Fluid. Skip White distributor. 20's, Z28 Cluster, Corbeau GTS Seat
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post #7 of 11 (permalink) Old 08-06-2018, 07:09 AM Thread Starter
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Junior,
I have been using the method you recommended and it works quite well. Then my old blower quit on me-slowed down and then wouldn't turn at all. Motor was pretty hot when I pulled it out. Very noisy inside the motor when I turn it by hand. Scored an OEM unit at the JY on Sunday :-) Put a couple drops of oil to pickle on the shaft and will install it today. Also set alerts at the local JY for any b-body wagons so I can stockpile.
Thanks for your help.

1994 Caprice Wagon-3.42|Impala SS Wheels/9C1 Wheels|Centrix Rotors|Fleetwood J55 Calipers|Koni Fronts, Monroe SS Rear|Bonneville 6 ways|Z28 Cluster|Pypes X-pipe|Dynomax Super Turbo's|[email protected]
1991 OCC|'93 Z28 LT1| ZZ4 Cam|SLP TC|Home Depot CAI - SOLD|[email protected]??
1983 Camaro Z28-I bought it new|5 speed|350 4 bolt|'90 Corvette heads, SLP headers and 3" exhaust|Konis|4 wheel discs|3.73. SOLD
2002 Regal GS|XP Comp Cam|SLP headers|3" downpipe|3.3 pulley|[email protected] (traction limited) SOLD


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post #8 of 11 (permalink) Old 08-06-2018, 08:25 AM
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Quote:
Originally Posted by Fullmoonboogie2002 View Post
Junior,
I have been using the method you recommended and it works quite well. Then my old blower quit on me-slowed down and then wouldn't turn at all. Motor was pretty hot when I pulled it out. Very noisy inside the motor when I turn it by hand. Scored an OEM unit at the JY on Sunday :-) Put a couple drops of oil to pickle on the shaft and will install it today. Also set alerts at the local JY for any b-body wagons so I can stockpile.
Thanks for your help.
No problem on the help, glad I could help make a difference.

Do you recall what color squirrel cage was on the motor you got? I ask only because there's an OEM style and an aftermarket, and the latter is approximately 1/2" shorter, and therefore moves less air

I looked real quick on my PC here at work, and know I've got some pictures for comparison. But hopefully since it was a junk yard dog it should be an OEM unit.

Clear Image Tri-Ys & Hi-Flow cats >> 2.5" X-Pipe & Magnaflow Tri-Chambers, Mike Harris 4L60E, Circle-D 2,400 RPM TC, All MOOG FT End & Del-A-Lum bushed MOOG CTRL Arms, Eibach FT & New Stock HT rear springs. Hotchkis Sway Bars & End Links, RAISS, 3.73 Gears in Eaton carrier, Dynoshaft & CIA Loop, BMR Trailing Arms, Braided Brake Hoses, Taylor Spiro-Pro Wires, AutoMeter Water Temp & Oil PSI Gauges, Impala Console. ATE Blue Brake Fluid. Skip White distributor. 20's, Z28 Cluster, Corbeau GTS Seat
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post #9 of 11 (permalink) Old 08-06-2018, 08:59 AM
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I'll try again.
Since it's that time of year for A/C problems. When I took my dash off I found this. The foam was stuck to the plastic. I can't figure out how this happened. I have some foam from packing I may try to duplicate.

Mark: Snowman-33
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93 9C1: Work & Cubic Ca$h This started with a new headlight and fender Celeritas In Conficiendo
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post #10 of 11 (permalink) Old 08-06-2018, 09:29 AM Thread Starter
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This car has had R134 when I bought it in 2008. Had to replace the compressor then because the clutch was bad. New R134 compressor was identical to the one I took out. The previous owner had copious notes on service and repair and nothing showed the conversion being done. There are no indications that it has been converted from R12.
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