steve meltzer

Factory A/C on my '66 BB can run great, cold, when it runs, but sometimes, for no apparent reason, it blows hot, but moments later if you've turned it off and you try again, it works fine. Doesn't change from hot to cold or cold to hot once it's decided where it wants to run. So, once running, it stays in that mode. It only fluctuates when it's been off, then switched on again. As you can imagine this is hard to trace. Any thoughts here? Obviously, it's full charged, or it wouldn't be cold, ever. thanx steve

Nowhere Man

Have you checked the hot water shut off valve or the vacumn switch on top of the heater box?

Powershift

That is always a possibility, but a leaking hot water valve by itself is not that big a deal. Only if the heater box interior seals and doors are also bad.

My money is on a sticking STV valve (or perhaps POA valve if you changed over to it). That is where I would concentrate my efforts.

Larry

steve meltzer

thanx so much for your ideas. i'll post when solved. thanx. s

steve meltzer

Not sure who put my AC system together years ago, tho' it works great under normal circumstances....replaced the heater fan resistor (common GM part) and the cycling switch/valve (from a 2000 or so Chrysler!!). Working great now. thanx steve

Avispa

Did you check the compressor clutch to be sure it engages reliably when current it put to it? They do develop intermittent failures once in a while.

steve meltzer

didn't specifically test that, but, if it fails again, I will. So far, so good. steve