1999 Buick Regal Blows cool then heat

Tiny
JHCHIL99
  • MEMBER
  • 1999 BUICK REGAL
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 201,000 MILES
After changing the battery the AC did not work properly. To get the AC working, I would have to adjust the fan speed, wait for the exterior temp. To appear and then hit the fan button again to get the AC to work. After about 15-20 minutes the vents on the driver's side would start blowing hot air but the passenger side vents would still be blowing cold air. What could be causing this?
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Thursday, April 29th, 2010 AT 8:27 AM

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Tiny
MERLIN2021
  • EXPERT
When you replaced the battery, did you remove the negative cable first, and attach it last? Try that first, then this is the test for the left side air temp not changing:
LEFT OUTLET TEMPERATURE DOES NOT CHANGE 1. Check for faulty HVAC (10-amp) fuse in instrument panel fuse block. If fuse is okay, go to next step. If fuse is open, go to step 3. 2. Check for a short to ground in Brown wire between instrument panel fuse block and A/C- heater control unit. Go to step 8. 3. Disconnect left-side temperature valve actuator connector. Turn ignition switch to RUN position. Using a DVOM, measure voltage between left-side temperature valve actuator harness connector terminal No. 5 (Brown wire) and ground. If voltage is 9-14 volts, go to step 5. If voltage is not 9-14 volts, go to next step. 4. Check for poor connection or open in Brown wire between left-side temperature valve actuator and HVAC (10-amp) fuse. Go to step 8. 5. Using a DVOM, measure voltage between left-side temperature valve actuator harness connector terminal No. 6 (Blue wire) and ground. Switch driver' temperature from full cold to full hot. Voltage should vary between.5 and 4.5 volts. If voltage varies as specified, replace left-side temperature valve actuator. If voltage does not vary as specified, go to next step. 6. Check for a short to ground or battery voltage in Dark Blue wire between left-side temperature valve actuator connector terminal No. 6 and A/C-heater control unit connector terminal C7. If wire is okay, go to next step. 7. Check for a poor connection or an open in Dark Blue wire between left-side temperature valve actuator connector and A/C-heater control unit. If wire is okay, go to next step. If wire is not okay, replace A/C-heater control unit. Go to next step. 8. Install a scan tool with appropriate cartridge and check for any DTCs that may be set. If any DTCs are set, go to appropriate DTC test. Page 1 of 1 4/29/2010 .
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Thursday, April 29th, 2010 AT 2:30 PM

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