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68 factory a/c with new compressor, filter-drier, expansion valve-134, cools some, not nearly enough. Seems to cool better until the motor gets hot-thinking it must have something to do with the heater door open or something. The compressor is plenty cool under the hood. I've also got this annoying little rattle on left turns with the fan on (sounds like an acorn-screw maybe) like maybe something is loose inside.

I want to drop the bottom of the plenum to see if I can locate the problem but don't have any intention of taking it all out from the firewall back. The clips are pretty easy to get out, but how hard are they to get back on with the plenum installed and will I gain anything by opening it up.

Anybody know if the heater core door is vacuum or cable operated?

Thanks.

J. Boggs
 

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I had to break out my vacuum diagram for in-das air, it's kind of obtuse but I'll try. The Center lever is the temperature control. It's the only cable control and does open and close the door between the evaporator and heater core. If your water valve is working correctly, there should be no hot water circulating through the core anyway. The forward vacuum motor close to the driver's right foot is the control for the "A/C-heat" door. Hmm, like I said-obtuse.
If all the controls appear to be functioning correctly, the seals might be worn. I replaced all mine before installing the assembly. Some of the old seals no longer even resembled anything useful.
You said you changed the compressor. Did you change to a Sanden or rotary-type compressor. I haven't had much luck trying to use the old York type with R134.
You didn't mention the condenser. the new replacements are 6 path compared to the original 3 path. Kinda like going from a 2 row radiator to a 4 row. I consider one of the newer type replacement condensers a necessity when changing over to R134. Some VMFers have had better luck than me though.
 

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Don't think you'll be able to drop the bottom half of the box off. The front facing you clips are easy but there are 3 or 4 on the backside that if do manage to get them off are not going to go back on cuz you won't have room to give them a whach to set them back in the groove AND you'll probably break off the edge of the groove they sit in. The clips don't just back on anyplae along the seam. They have to go back in the moulded offsets they sit in.
Taking bottom off won't really show anything so I wouldn't do that. I would look at the temp controll switch shich sits on the top left side of the bos towards the driver and two wires attached to two connectors..blade type. Perhaps wires on backwards or switch no good. You can get off by removeing the two screws and fishing the themocouple style sensor lead out of the box..it is running into a hole on side of evaporator that allows it to read thee temp.
Most of the foam insulation pieces that close of the doors can't be replaced without the whole box removed.
Surprised you didn't remove box to pull evap core to have cheecked before you charged system. You could of done the couple piecees of faom at that time and madde sure the door op. smoothly.
One other item..you did properly reattch the expansion valve "bulb" back on to the line at the firewall??
How did you get oil in evaporator. Some gpes in it along with the comp.
 

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Discussion Starter #4
Your switch idea might work-I was going to try to see if my switch was functional anyway.

I rebuilt the whole box and all the gut early on in my resto career so I was done but not with a great deal of expertise I don't think.

Thanks.

J. Boggs
 
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