HVAC controls question.`

[82355]

I am trying to fix the HVAC system in my 1975 K5 Blazer. The heater core is bad, the fan switch is broken, and the temperature blend switch is broken.

I stole parts from a 1988 K5 Blazer (heater core, and heater and AC evaporator box). They seem to be an almost exact match.


I then took the controls panel and temperture blend cable from a 1980 K5 Jimmy. The panel and controls are slightly different.

The 1975 control panel has no MAX AC setting. I am guessing that is the difference.

the 1975 control panel has two levers into the vacuum switch. One from the settings lever, and one from the temperature control lever.

The 1980 control has MAX AC. It also has only one lever into the vacuum control switch.

Can I make these parts work together? Anyone messed with this before?

I am thinking I can take the vacuum switches, and swap them along with the control panels?

I tried taking pictures. My phone died.

Martin

 

[6872xtc]

I can't tell you for sure, but I believe that you can make it work. The max a/c of course won't work unless you install the recirculation door in the cowl and the actuator on the kick panel vent. So I think you can plug the port for that and have the rest work.

 

[82355]

It has those parts.

I think the way it is set up is that it goes to recirculate when you move the temperature control lever all the way to COLD.

Martin

 

[82355]

So I compared the vacuum switches. The 1975 is much more complicated than the '80, with many more ports.

So them I took the HVAC controls out of a '74 K20 I have.

That was a pain. The '75 and '80 control panels are mounted in front of the steel dash structure. The '74 control panel is mounted behind the steel panel. I had to remove the radio and the gauge cluster to get it out.

By looking at the function of this, I believe the '74-'75 setup goes to MAX AC (recirculate) by just sliding the temperature blend switch all the way to cold like I thought.

Martin

 

[6872xtc]

Well hopefully you get it figured out as apparently I don't have any info to help. ...

 

[blazer74]

Max A/C is all the way to cold.

 

[blazer74]

Also puts the blower on high regardless of switch position via the single orange wire to the switch from the vac control assuming it's the original configuration.