No cooling, driver's side only

Tiny
FOOTEWI
  • MEMBER
  • 2000 BUICK LESABRE
Six cylinder front wheel drive automatic 126,000 miles.

With air conditioner on, I get cooling on passenger side only. Warm (ambient) air on driver side. This is a manual system; there is only one air mix actuator for both passenger and driver side. All three actuators (air mix, mode and re-circulation) seem to be working properly. This system does not use any vacuum controls. Actuators have been re-calibrated (by removing 10 amp fuse in rear fuse block). A/C system hi and low side pressures are within spec. Thanks.
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Thursday, August 12th, 2010 AT 4:14 PM

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Tiny
MERLIN2021
  • EXPERT
If you do not mind me asking, what is the readings of the high and low side, and temperature and humidity when readings are taken? The most common reasons are low charge, too much oil in the system, and weak compressor. Maybe a bad cycling switch. When you hook up your gauges, take note of not only the readings, but count the cycling time of the compressor, when it starts, count the time until it turns off, then the time it remains off until it restarts, post all her. A scan of the B and U codes may also be helpful. Also, is this an auto temperature or manual A/C system? My suggestion is to take it to a shop with an A/C recharging machine, have it evacuated, vacuumed and recharged by machine, R134a is picky about accuracy, and is next to impossible to get right, even for experienced techs. And the new machines will hold the vacuum until they know there are no leaks.
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Thursday, August 12th, 2010 AT 4:39 PM
Tiny
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The air conditioner is working fine. I have excellent cooling on passenger side, with AC outlet temperature of about fifty five degrees. The problem is with the the air distribution system.
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Thursday, August 12th, 2010 AT 8:56 PM
Tiny
MERLIN2021
  • EXPERT
Fifty five degrees is poor output at any register, on any A/C system, on any car! I have been doing A/C on all makes and models, the theory behind A/C is the same for all units. This is the usual problem found for your condition.
Also, you are telling me your pressure readings are in spec, but you do not post them, so what am I supposed to base a diagnosis on other than general information.
99.9% of units that have this condition is low charge, weak compressor. Or stuck temperature door. But you state all is well? Scan for B and U codes if the base system is okay, this will pinpoint any stuck doors, or bad sensors. These codes will not turn on your service engine light.
You might want to remove the actuator to check for broken parts, they are only plastic gears, and if the door is stuck, the actuator can break. The other problem is, re-calibrating the actuators by fuse removal may work, but it is not the preferred method, if codes are store it will not work, and if you pressed any buttons before the forty seconds wait re-calibration period, it will not work.
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Friday, August 13th, 2010 AT 6:47 AM
Tiny
FOOTEWI
  • MEMBER
Okay by the numbers:

I just went out and checked them again, to be sure I am not leading myself (and you) down the wrong path.

1. Ambient temperature seventy two degrees (about twenty degrees colder than the last time I checked the system). Relative humidity (guess) fifty percent (about twenty five percent lower than the last time I checked system).
2. Passenger side A/C register temperature forty six degrees! (Twenty six degrees below ambient). Driver side A/C register temperature around sixty five. (Just below ambient, which is sort of interesting).
3. High side pressure 190.
4. Low side pressure 33.
5. Compressor clutch engaged full time (at least for the five to ten minutes I observed it). No cycling at all.
6. No trouble codes observed using my OBD II reader.

These number are within the specs of the third party (Mitchell) manual I have. I do not have a Buick shop manual.

So, to me, the air conditioner (that is, the condenser/compressor/expansion tube) is working okay. It is the distribution system (what would be an air handler in a home A/C) that is messed up. It is acting like like I am on A/C on one side and vent on the other. That is why I am asking for your help. How can I be getting conditioned air on one side, and ambient air on the other? Are there a separate air flows for driver and passenger sides? If yes, where are the doors/linkages/whatever? How do I adjust/fix them?
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Friday, August 13th, 2010 AT 9:07 AM
Tiny
MERLIN2021
  • EXPERT
Okay, both readings are too warm for your current temperature and humidity, also the clutch should be cycling at these temperatures, the hotter it gets outside the less cycling it should do. The other thing to quickly look at is the floor wet on the passenger side?
By the book driver's side too warm:
DRIVER'S-SIDE TEMPERATURE CONTROL SELECTOR INOPERATIVE 2000 Models (Single & Dual Zone Systems) 1. Check HVAC (10-amp) fuse in instrument panel fuse block. If fuse is okay, go to step 3. If fuse is blown, go to next step. 2. Check for short to ground in Brown wire between instrument panel fuse block and A/C-heater control panel Black 12-pin harness connector C2 terminal "C". See Fig. 3 . Repair Brown wire as necessary. After repair, go to step 18. 3. Turn ignition switch to OFF position. Disconnect A/C-heater control panel Black 12-pin harness connector C2. Using a DVOM, measure voltage between A/C-heater control panel harness connector C2 terminals "C" (Brown wire) and "K" (Black wire). If battery voltage does not exist, go to next step. If battery voltage exists, go to step 7. 4. Using a DVOM connected to ground, probe A/C-heater control panel harness connector C2 terminal "C" (Brown wire). If battery voltage does not exist, go to next step. If battery voltage exists, go to step 6. 5. Locate and repair poor connection or open in Brown wire between A/C-heater control panel Black 12-pin harness connector C2 terminal "C" and instrument panel fuse block. After repair, go to step 18. 6. Locate and repair poor connection or open in Black wire between A/C-heater control panel Black 12-pin harness connector C2 terminal "K" and ground. See WIRING DIAGRAMS . After repair, go to step 18. 7. Turn ignition switch to OFF position. Reconnect A/C-heater control panel harness connector C2. Disconnect left electric actuator. Turn ignition switch to ON position. Connect DVOM between left actuator harness connector terminal No. 7 (Black wire) and terminal No. 10 (Brown wire). If battery voltage does not exist, go to next step. If battery voltage exists, go to step 11. 8. Using a DVOM connected to ground, probe left actuator harness connector terminal No. 10 (Brown wire). If battery voltage does not exist, go to next step. If battery voltage exists, go to step 10. 9. Repair poor connection or open in Brown wire between left electric actuator harness connector terminal No. 10 and instrument panel fuse block. See WIRING DIAGRAMS . After repair, go to step 18. 10. Check for poor connection or open in Black wire between left electric actuator harness connector terminal No. 7 and ground connector located behind right side of instrument panel. After repair, go to step 18. 11. Using DVOM connected to ground, probe left electric actuator harness connector terminal No. 8 (Dark Blue wire). Move temperature control lever from COLD to HOT, and from HOT to COLD positions. If indicated voltage varies 1-12 volts, go to next step. If indicated voltage does not vary 1-12 volts, go to step 13. 12. Replace left electric actuator. After repair, go to step 18. 13. Check for short to ground in Dark Blue wire between A/C-heater control panel harness connector C2 terminal "G" and left electric actuator harness connector terminal No. 8. If a short to ground is present, go to next step. If a short to ground is not present, go to step 15. 14. Repair short to ground in Dark Blue wire between A/C-heater control panel harness connector C2 terminal "G" and left electric actuator harness connector terminal No. 8. 15. Check for poor connection or open in Dark Blue wire between A/C-heater control panel harness connector C2 terminal "G" and left electric actuator harness connector terminal No. 8. If problem is found, go to next step. If no problem is found, go to step 17. 16. Repair Dark Blue wire between A/C-heater control panel harness connector C2 terminal "G" and left electric actuator harness connector terminal No. 8 as necessary. After repair, go to step 18. 17. Replace A/C-heater control panel. See A/C-HEATER CONTROL PANEL under REMOVAL & INSTALLATION. After repair, go to next step. 18. Operate system to verify repair. If driver's side temperature control operates normally, repair is complete. If driver's side temperature control does not operate normally, return to step 1.


http://www.2carpros.com/forum/automotive_pictures/62217_Ac_Air_control_1.jpg



http://www.2carpros.com/forum/automotive_pictures/62217_Specs_5.jpg



http://www.2carpros.com/forum/automotive_pictures/62217_pressures_1.jpg


Low side at 50% humidity is a bit low, Raise idle to 2000 with gauges attached, low side will drop, when it gets to 23 the compressor should cycle off. Your orifice tube may be over 90% clogged, they can work up to that point.
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Saturday, August 14th, 2010 AT 7:59 AM
Tiny
FOOTEWI
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Thanks for your help. Problem solved.
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Sunday, August 22nd, 2010 AT 4:49 AM
Tiny
MERLIN2021
  • EXPERT
You are welcome.
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Sunday, August 22nd, 2010 AT 10:50 AM

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