Evaporator Core Access and Cleaning - The 1947 - Present Chevrolet & GMC Truck Message Board Network

kna4977 · 08-23-2025, 09:57 PM

1972 factory A/C. Can't seem to get my system to cool like it should. No leaks, everything is clean, lots of new parts. Only thing I haven't done so far is inspect/clean/replace the evaporator core. Can it be cleaned without removing the box that contains it under the hood on the passenger side? If so, how?

Hidesertchevy · 08-24-2025, 01:45 AM

Cleaning the evaporator requires removing the box under the hood.

**Richard** · 08-24-2025, 03:05 AM

Removing fender liner makes removal easier. 50+ years old. Maybe worth a look at it.

kna4977 · 08-24-2025, 04:41 PM

Could you not leave the box attached and the inner fender in place and just remove the inner side of the box to inspect and clean the core?

kna4977 · 08-26-2025, 10:02 PM

This is why I ask if it's possible and if anyone on here has tried and done it successfully. Truck in the video looks to be 73 or later. I'm thinking a 75 or so. It has a little different setup and some different A/C components. The video is titled 67-87. Before I attempt it, can anyone confirm if this will work on a 67-72?

https://youtu.be/M4hGULHGo6U?si=9Z559ocu_Aq_wgdD

**71CHEVYSHORTBED402** · 08-26-2025, 10:21 PM

Worth a try if depressurized I guess. Wow the sludge on that core, I've never seen that, though who knows how long my system wasn't running.

If you think the gaskets will be compromised, especially on the firewall, I'd do what Richard said, and then pull it off. May as well address the heater core while you're at it, if due, sure hate to do that back to back☺

If you're running R134A with a basically original system, it's not going to cool like R12.

**leddzepp** · 08-27-2025, 01:55 PM

Quote:

Originally Posted by 71chevyshortbed402

if you're running r134a with a basically original system, it's not going to cool like r12.

this 100% ^^^

kna4977 · 08-27-2025, 09:15 PM

Quote:

Originally Posted by leddzepp

this 100% ^^^

I've read that too, but why not if the POA is calibrated correctly? I've done other R12 systems to R134 and they are r12 equivalent ice cold, but they do have different components. Orifice tube and accumulator vs the POA and expansion valve on this system.

Rick Bollinger · 08-27-2025, 09:56 PM

I did mine 100% stock except compressor that's a Sandan. Completely cleaned everything adjusted POA, 134 no problems except some noise. Just be ready to replace your blend door in the box. My new one took some trimming to get it to seal correctly. O rings are cheap, door not to bad either. Cools just fine.

08-23-2025, 09:57 PM	#1
kna4977 Senior Member Join Date: Jul 2006 Location: DFW Posts: 571	Evaporator Core Access and Cleaning 1972 factory A/C. Can't seem to get my system to cool like it should. No leaks, everything is clean, lots of new parts. Only thing I haven't done so far is inspect/clean/replace the evaporator core. Can it be cleaned without removing the box that contains it under the hood on the passenger side? If so, how?

08-24-2025, 01:45 AM	#2
Hidesertchevy Registered User Join Date: Mar 2017 Location: yucca valley Posts: 318	Re: Evaporator Core Access and Cleaning Cleaning the evaporator requires removing the box under the hood.

08-24-2025, 03:05 AM	#3
Richard Senior Member Join Date: Dec 1999 Location: Southern California Posts: 3,346	Re: Evaporator Core Access and Cleaning Removing fender liner makes removal easier. 50+ years old. Maybe worth a look at it. __________________ Richard 1972 K10 Custom Deluxe SWB Fleetside My build https://67-72chevytrucks.com/vboard/...d.php?t=800746

08-24-2025, 04:41 PM	#4
kna4977 Senior Member Join Date: Jul 2006 Location: DFW Posts: 571	Re: Evaporator Core Access and Cleaning Could you not leave the box attached and the inner fender in place and just remove the inner side of the box to inspect and clean the core?

08-26-2025, 10:02 PM	#5
kna4977 Senior Member Join Date: Jul 2006 Location: DFW Posts: 571	Re: Evaporator Core Access and Cleaning This is why I ask if it's possible and if anyone on here has tried and done it successfully. Truck in the video looks to be 73 or later. I'm thinking a 75 or so. It has a little different setup and some different A/C components. The video is titled 67-87. Before I attempt it, can anyone confirm if this will work on a 67-72? https://youtu.be/M4hGULHGo6U?si=9Z559ocu_Aq_wgdD

08-26-2025, 10:21 PM	#6
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,692	Re: Evaporator Core Access and Cleaning Worth a try if depressurized I guess. Wow the sludge on that core, I've never seen that, though who knows how long my system wasn't running. If you think the gaskets will be compromised, especially on the firewall, I'd do what Richard said, and then pull it off. May as well address the heater core while you're at it, if due, sure hate to do that back to back☺ If you're running R134A with a basically original system, it's not going to cool like R12. __________________ Tony 1971 C10 Custom Deluxe SWB 402/400TH A/C I developed an assembly information kit for restoring my truck from nuts and bolts. It's written in Assy. order, short & simple, packed with all OEM hardware ID; castings; part ID; 100s of part numbers; wiring simple - Resource, and trivial too. Much info. applies to all 67-72 GM, A/C vehicles, esp. trucks W/O saying. Full search ability, including to 700+ images of illus., parts, charts, Assy., points of interest, cab, bed, & front clip cart plans- Specials and cores were serviced out and R excluded e.g. front/rear glass, body/paint, engine core, rebuilt hinges, steering box, trans, etc. The project was in-line with long former professions developing process, policy, specs, demo, written for novices, admin., policy, engineers, development, systems & test - Public & govt 2, gross. Sell soft copy cheaply, PM if interested.Build thread:https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 08-26-2025 at 10:26 PM.

08-27-2025, 09:56 PM	#9
Rick Bollinger Registered User Join Date: Mar 2018 Location: Colchester IL Posts: 512	Re: Evaporator Core Access and Cleaning I did mine 100% stock except compressor that's a Sandan. Completely cleaned everything adjusted POA, 134 no problems except some noise. Just be ready to replace your blend door in the box. My new one took some trimming to get it to seal correctly. O rings are cheap, door not to bad either. Cools just fine.



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