12-24-2017 | #1 |
Join Date: Dec 2005
Location: Delanson, NY
Posts: 914
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HVAC issues on a 1990
I posted a while ago, pulled the heater core to get to the actuator since I had no heat only AC. Tried two different actuators, when I switch to heat, temp at 90 degrees the blend door pulses open and closes about a quarter inch. Spoke to Bryan Thompson he thought it might be the programmer. Pulled the programmer, control head and shipped them to BATEE with the actuators.
Bryan tested with my actuators found one with a broken gear but the two others would pulse the door when calling for heat. He tells me it works fine with his actuator so he ships it back and I buy a brand new actuator from AC Delco. Install the parts, power up the car and it pulses when calling for heat. I find no open circuits, but the power to the actuator when calling for heat pulses between 7.6 volts and 0.5 volts. When calling for AC the power remains steady at 7.6 volts. POT input just below 5.0 volts per the FSM. Bryan claims there is nothing wrong with the programmer or control head, but I can not figure out why it pulses when calling for heat. Anyone out there have any ideas? Thanks in advance and Merry Christmas to all!
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1968 convertible Lemans Blue, 1986 coupe Medium Blue NCRS Top Flight (sold), 1990 ZR1 #2529 Red NCRS Regional and National Top Flight (sold), 1990 ZR1 #2124 Charcoal Metallic NCRS Top Flight 2010 & 2018, 2003 Anniversary Red Convertible (sold) |
12-24-2017 | #2 |
Join Date: May 2007
Location: Westminster, Maryland
Posts: 3,689
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Re: HVAC issues on a 1990
Please describe what you are observing that you call "pulsing"? What position are you referring to when you say "closes a quarter inch"? ("blocking air flow thru the heater core"? or blocking air flow thru the AC evaporator?)
With the thermostat set at 85 degrees, the blend door should move all the way to block air flow through the AC evaporator coils. In my 1994, the blend door moved smoothly and continuously to its commanded position. When the ignition is turned ON, the blend door should move full travel in one direction and then full travel in the opposite direction. The HVAC programmer needs to be reset by disconnecting the battery for 30 seconds after any changes to the system. Have you been doing that? Jim
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If it isn't fun, you aren't doing it right! 1990 Black ZR-1 - sold 1993 Quasar Blue ZR-1 1994 Competition Yellow ZR-1 1995 Dark Purple ZR-1 Maryland State Coordinator WAZOO Member Last edited by QB93Z; 12-24-2017 at 05:33 PM. |
12-24-2017 | #3 | |
Join Date: Dec 2005
Location: Delanson, NY
Posts: 914
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Re: HVAC issues on a 1990
Jim, responses below in red.
Quote:
Update: spent about 1/2 the day disconnecting and reconnecting the power and trying to get the blend door to calibrate. Tried two different actuators and also the new one. All give the same symptoms. Even tried hooking up the CDM and the blower resistor, thought that might be the problem. Blower works all speeds, and is not locked out at startup calibration like FSM says it should. This leads me to think the problem is lack of calibration. Where does the commands for calibration come from; programmer, control head, other?
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1968 convertible Lemans Blue, 1986 coupe Medium Blue NCRS Top Flight (sold), 1990 ZR1 #2529 Red NCRS Regional and National Top Flight (sold), 1990 ZR1 #2124 Charcoal Metallic NCRS Top Flight 2010 & 2018, 2003 Anniversary Red Convertible (sold) Last edited by jrd1990zr1; 12-25-2017 at 04:42 PM. |
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02-28-2018 | #4 |
Join Date: Nov 2017
Location: Santa Barbara CA
Posts: 51
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Re: HVAC issues on a 1990
Was this ever resolved? I'm having similar issues. Blend door moves full travel and heater hoses are hot.
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1993 Bright Aqua Metallic # 027 |
03-01-2018 | #5 | |
Join Date: Dec 2005
Location: Delanson, NY
Posts: 914
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Re: HVAC issues on a 1990
Quote:
If your car is a 1993 then I think the actuator is on the bottom of the box and easy to get to. Good luck, I don't want to ever have to do this job again.
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1968 convertible Lemans Blue, 1986 coupe Medium Blue NCRS Top Flight (sold), 1990 ZR1 #2529 Red NCRS Regional and National Top Flight (sold), 1990 ZR1 #2124 Charcoal Metallic NCRS Top Flight 2010 & 2018, 2003 Anniversary Red Convertible (sold) |
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03-03-2018 | #6 |
Join Date: Nov 2017
Location: Santa Barbara CA
Posts: 51
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Re: HVAC issues on a 1990
Thank you for the input. My blend door seems to move fine and hot coolant is flowing, but still get cold ambient air. Might be a different issue. Glad you got yours fixed!
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1993 Bright Aqua Metallic # 027 |
03-04-2018 | #7 |
Join Date: Dec 2005
Location: Delanson, NY
Posts: 914
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Re: HVAC issues on a 1990
Are there any lights blinking on the control head, may have a code stored.
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1968 convertible Lemans Blue, 1986 coupe Medium Blue NCRS Top Flight (sold), 1990 ZR1 #2529 Red NCRS Regional and National Top Flight (sold), 1990 ZR1 #2124 Charcoal Metallic NCRS Top Flight 2010 & 2018, 2003 Anniversary Red Convertible (sold) |
03-05-2018 | #8 | |
Join Date: Nov 2017
Location: Santa Barbara CA
Posts: 51
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Re: HVAC issues on a 1990
Quote:
One thing I'm concerned about is the A/C was rebuilt on it before I got it. I'm not sure what was done and if that would have any impact on the electronic control.
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1993 Bright Aqua Metallic # 027 Last edited by SBAquaLT5; 03-05-2018 at 09:29 PM. |
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