This is part 1 of a series of posts to document some of the stuff I did to fix my HVAC.

At this point what’s done:

Rebuilt heater core box and blower/air intake box. Currently they are back in the car but not the evap box, vents or dash. This involved replacing all 3 actuators with cheap aftermarket ones. The 3 bellows were still functioning.

Disassembled/reassembled vacuum pump and vacuum tank and lubricated orings (ideally you should replace these)

Replaced AC compressor

And what still needs to be done:

Rebuild evap (replace orings), put evap box back into car

Replace o-rings on everything in the engine bay

Charge AC system / final tests

Quick Background

My Z’s heater and AC didn’t work when I first got it. On top of that the thermostat got stuck at one point and ruptured a leak on the heater core. So until recently I had bypassed the heater core to prevent flooding my interior.

Since I live in TX I wanted A/C so I can drive the car any time of the year. But this car is R12/freon so first my plan was to replace all of the o-rings with HNBA so I could convert to r134a. Part of this job requires removing the A/C evap in the car to replace all of its o-rings. This requires removing the dash and all of the vents. While I’m in there I may as well fix the heater core. And on top of this, spoiler alert, almost none of the vacuum actuators were functional. So time to fix all of that. The goal of this page is to 1) list out some of the aftermarket parts I used and how I made them work and 2) dump a lot of reference photos.

The project isn’t done yet (few more weeks) but the heater box is fully functioning and reinstalled at this point.

Stuff I Had To Buy

A large amount of the job was just dismantling stuff, cleaning it, lubricating, and putting back together. All of the old foam was either worn away or super brittle and useless. I cleaned that off and replaced with various weather stripping foams from Walmart / Amazon (maybe $30 worth in the end).

I purchased all of the cheap Dorman vacuum actuators I could find on Amazon to see what could work where. In the end I was able to make all 3 of these work and didn’t have to buy any others. 2/3 of the ones I bought were Amazon warehouse deals and extra cheap – both normally closer to $15. Buying functional used actuators is closer to $100/each. For all 3 I had to manually design/3d print some mounts so that these actuators would work. 2/3 I had to modify in some way (saw off some of the linkage and/or bend linkage, clip off some of the plastic mount area)

First I purchased an HNBR o-ring kit from RockAuto, but this was useless. Just buy a $5 harbor freight assortment. There are a few sizes of o-rings you’ll need beyond that though and I got those from the O-Ring Store. These are in the evap. You need 2x of the 026 size and only 1x of the other two. I got the Viton one because the HNBR minimum quantity was like 250. Shipping cost more than the o-rings.

At first I ordered a heater core that was recommended for the Z but it was around $100. I ended up returning it and getting one from Amazon that I made work. It’s a little undersized but we’ll see if it heats up the car soon enough. I also ordered a relief valve since I’m not sure on the condition of the original. I also bought 50ft of vacuum line and used the majority of it. The vacuum pump is optional but was useful for troubleshooting.

Item Price 57433 3Seasons/Everco/A/C Compressor 308.49 XtremepowerUS Vac Pump and Manifold Gauge Set 129.50 Spectra Premium 94576 Heater Core 33.32 Various weather stripping foam 30.00 50ft Gates 27041 Vacuum Hose 23.47 12V Vacuum Pump 20.95 Dorman 604-934 Vacuum Style Air Door Actuator 15.89 SW 2155C A/C Receiver Drier Pressure Relief Valve 15.82 1x AS568-021 HNBR (HSN) Highly Saturated Nitrile 70 Duro O-Ring (H70021) 8.50 2x AS568-026 HNBR (HSN) Highly Saturated Nitrile 70 Duro O-Ring (H70026) 1x AS568-029 GV75 Green Viton (FKM, Fluorocarbon) 75 Duro O-Ring (GV75029) 1311567 A/C System Valve Core and Cap Kit 7.48 RD1168C A/C Receiver Drier / Accumulator 7.38 Dorman OE Solutions 604-922 Vacuum Style Air Actuator 6.77 Dorman 604-933 Vacuum Style Air Door Actuator 6.39 Heater Core Firewall Grommet 90480-01405 ($3.70+S/H) 11.11 Misc (HF oring assortment, hose clamps, brushes, cleaners, etc) 50.00 Project Total 613.96

Probably more expenses as I wrap up the project, but this is most of it.

Modifying and Mounting the New Actuators

Intake actuator – Dorman 604-934

3d printed mount: https://a360.co/2BFQEDM

This one was the easiest to use and mount. No need to modify the linkage, just remove the e-clip from the current one and swap. This one happens to be a 2 stage actuator just like the one it’s replacing. I’m not sure if the angle of the door is going to end up the same but hopefully it will work.

Power Servo 1 – Dorman 604-922

3d printed mount: https://a360.co/2BH1ysF

I sawed off the last 2 inches of so. Then I put a right angle and used the already drilled hole to butt against the existing hardware. I also used the mounting slots to attach the 3d printed mount.

Power Servo 2 – Dorman 604-933

3d printed mount: https://a360.co/2BHQCeJ

I had to cut off a few things from this one. First I trimmed all of the plastic off that is meant for mounting the actuator. Then I sawed off the last piece of the linkage.

This actuator had too much travel vs the original one. You can see in the picture above how I took care of that. The first 1/2 in of travel is doing nothing while the next 1 in of travel actuates the assembly.

Adapting the Heater Core

I sawed up a bunch of foam to make the profile of the smaller heater core fit in the slot. There are foam strips along the sides to make an air tight seal.

I still need to figure out mounting the solenoids for the air intake door.