A couple factory AC questions. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

rmneder · 08-03-2020, 03:59 PM

I'm getting my factory AC back together. I don't have the compressor installed yet but I've got the interior part all together. I've been messing with the controls and when I set the lever to inside air the passenger side kick panel vent opens. I've never had working air conditioning in this truck so I don't know for sure, but shouldn't the vent open when the controls are set to outside air? Also when not in use and the fan off, what is the off position for the three levers. Does it matter what position they're in? Thanks.

**71CHEVYSHORTBED402** · 08-03-2020, 05:14 PM

Here's some notes from my tear-down you might find helpful. They have to be edited when I assemble it, but it's a start:

Top lever on the control unit (INSIDE/OUTSIDE - AIR/DEFROSTER selector):
• The cable connects from the top lever to the Air/Defroster Selector Duct. The top lever also operates the air door (RH kick panel & cowl) actuators.

• When the unit is set to INSIDE the heater water control valve closes water flow to the heater core, and the air doors close.

Irregularity: This was the only cable on the unit with a push-on retainer nut.

Middle lever on the control unit (A/C & HEATER): The cable connects from the middle lever to the Duct Air Selector. It diverts the airflow for the floor duct and A/C vents. The A/C compressor switch is triggered when set to A/C.

Bottom lever on the control unit (COLD / HOT): The cable connects from the bottom lever, routes through the firewall, and connects to the rod for the A/C Heater door on the evaporator box. The hole in the firewall is outside of the well, near the top RH corner of the well. This door directs airflow through the heater core, evaporator core or both.

sick472 · 08-03-2020, 05:46 PM

The passenger side kick vent should close and the one in the cowl area should open for "outside air". For inside air...it's the opposite. When the cowl vent closes and the kick vent opens...the fan will pull air from inside the cab and recondition it. The opposite would pull air from only the outside.

08-03-2020, 03:59 PM	#1
rmneder Registered User Join Date: May 2012 Location: San Diego Posts: 86	A couple factory AC questions. I'm getting my factory AC back together. I don't have the compressor installed yet but I've got the interior part all together. I've been messing with the controls and when I set the lever to inside air the passenger side kick panel vent opens. I've never had working air conditioning in this truck so I don't know for sure, but shouldn't the vent open when the controls are set to outside air? Also when not in use and the fan off, what is the off position for the three levers. Does it matter what position they're in? Thanks.

08-03-2020, 05:14 PM	#2
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,118	Re: A couple factory AC questions. Here's some notes from my tear-down you might find helpful. They have to be edited when I assemble it, but it's a start: Top lever on the control unit (INSIDE/OUTSIDE - AIR/DEFROSTER selector): • The cable connects from the top lever to the Air/Defroster Selector Duct. The top lever also operates the air door (RH kick panel & cowl) actuators. • When the unit is set to INSIDE the heater water control valve closes water flow to the heater core, and the air doors close. Irregularity: This was the only cable on the unit with a push-on retainer nut. Middle lever on the control unit (A/C & HEATER): The cable connects from the middle lever to the Duct Air Selector. It diverts the airflow for the floor duct and A/C vents. The A/C compressor switch is triggered when set to A/C. Bottom lever on the control unit (COLD / HOT): The cable connects from the bottom lever, routes through the firewall, and connects to the rod for the A/C Heater door on the evaporator box. The hole in the firewall is outside of the well, near the top RH corner of the well. This door directs airflow through the heater core, evaporator core or both. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s of OEM identifications and part numbers, all written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025

08-03-2020, 05:46 PM	#3
sick472 Registered User Join Date: Jul 2015 Location: Sedalia Mo. Posts: 1,130	Re: A couple factory AC questions. The passenger side kick vent should close and the one in the cowl area should open for "outside air". For inside air...it's the opposite. When the cowl vent closes and the kick vent opens...the fan will pull air from inside the cab and recondition it. The opposite would pull air from only the outside. __________________ He who is without oil shall throw the first rod. Compressions 8.7:1 1972 C10 1976 C10 (parts truck) 1985 K20



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