Manual Heater Swap

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Ratrod312

Newbie
Joined
Aug 8, 2021
Messages
48
Reaction score
50
Location
Tampa, fl
Anyone know what all is involved in swapping from a regular AC controller to a manual Heater setup? Do I need to replace everything AC-wise behind the dash?
 

Attachments

  • IMG_20220119_111036630.jpg
    IMG_20220119_111036630.jpg
    279.1 KB · Views: 16
  • IMG_20220119_111136569_HDR.jpg
    IMG_20220119_111136569_HDR.jpg
    204.4 KB · Views: 16

DerekTheGreat

Forum Regular
Joined
May 23, 2016
Messages
1,582
Reaction score
1,612
Location
Michigan
I don't know everything, far from it actually. But, I believe the heater box is different between the two as the digital controller employs servo motors to control the blend doors. Also, if you have A/C and intend to keep it, they never made a manual A/C control head. All A/C trucks had digital controllers.

Why do you want to do the conversion? The electric stuff is actually pretty reliable. I've had my '89 for over four years now with no issues. It had one bad servo motor when I got the truck, replaced it and have been fine ever since.
 

Ratrod312

Newbie
Joined
Aug 8, 2021
Messages
48
Reaction score
50
Location
Tampa, fl
I don't know everything, far from it actually. But, I believe the heater box is different between the two as the digital controller employs servo motors to control the blend doors. Also, if you have A/C and intend to keep it, they never made a manual A/C control head. All A/C trucks had digital controllers.

Why do you want to do the conversion? The electric stuff is actually pretty reliable. I've had my '89 for over four years now with no issues. It had one bad servo motor when I got the truck, replaced it and have been fine ever since.
I appreciate the info. My truck does not have working AC, and I hadn't really planned on ever getting the AC going. I figured if it were a simple swap I would go ahead and do it. I do use the truck's heater...when the AC controller decides to work that is.
 

someotherguy

Truly Awesome
Joined
Sep 28, 2013
Messages
10,006
Reaction score
14,720
Location
Houston TX
I'm reasonably sure you would swap the whole box. The dampers in the box are cable-operated on the manual heat setup, and I'm pretty sure the box is different to account for that.

Being from TX we don't see many non-A/C trucks here, they're pretty rare, so I could be wrong. I did look at a customer's non-A/C (old AT&T fleet) truck as he wanted to convert it to A/C. Big job, but totally do-able IMO. Why AT&T felt like their techs needed to work in TX heat without A/C, I'll never know.

Richard
 

Dropped88

Supporting Member
Supporting Member
Joined
Dec 25, 2017
Messages
1,313
Reaction score
3,177
Location
Georgia
I have seen a w/t with manual controls and ac. But the ac system was expansion valve style and not orfice tube appeared to been factory but thats been many years ago
 

Badams7725

Newbie
Joined
Jun 24, 2021
Messages
1
Reaction score
1
Location
Roanoke
You must be registered for see images attach

I don't know everything, far from it actually. But, I believe the heater box is different between the two as the digital controller employs servo motors to control the blend doors. Also, if you have A/C and intend to keep it, they never made a manual A/C control head. All A/C trucks had digital controllers.

Why do you want to do the conversion? The electric stuff is actually pretty reliable. I've had my '89 for over four years now with no issues. It had one bad servo motor when I got the truck, replaced it and have been fine ever since.
Here’s one right here
 

Attachments

  • 16977879-E237-48FD-91D1-7E273614A8BF.jpeg
    16977879-E237-48FD-91D1-7E273614A8BF.jpeg
    446.6 KB · Views: 16

someotherguy

Truly Awesome
Joined
Sep 28, 2013
Messages
10,006
Reaction score
14,720
Location
Houston TX
You must be registered for see images attach


Here’s one right here
Interesting. And that's gonna be at least a 1992 model based on the needle/non-tach cluster, and gray bezel/switch coloring. (rationale behind my thinking: 1988-1989 would have black bezel/switches and moonie gauges, 1990 would generally be gray but still have moonie gauges, 1991 would be moonie gauges or needles w/tach.)

Sure would like to see a picture of the SPID label on that truck if it's still legible, or a printout of RPO's from the dealer or Compnine on that truck.

In TX we're so used to seeing the regular A/C-equipped trucks, even on super base models, that you'd pretty much have a near-zero chance of seeing that type of control setup down here.

Where it could get confusing just scanning RPO's in the list is the RPO's used for A/C systems refer to both "manual" and "electronic" controls - BUT - electronic controls are still considered "manual" (RPO C60 for example, electronic controls in a 1993) because they don't have an automatic temperature setting. For what it's worth, pretty much everyone with an A/C-equipped GMT400 should be used to seeing C60 on their SPID label regardless of year, as it refers to the 88-94 trucks with the electronic controls as well as the 95-up with the dials, since they're still electronic, although no digital display like the earlier trucks.

Richard
 
Last edited:
Top