AC Blows hot Air During Acceleration

[buggs]

I've been chasing this issue since I bought the truck in August. Overall, the truck has been well cared for and runs great. Here are the issues:
1. When the AC is on, and I'm accelerating, the AC turns hot until the engine is no longer under "load". Once it's back to a cruising "load" (like an idle) and not accelerating, it goes back to cold AC. The RPMs, gear, or any other factors don't appear to be an impact. It's just when it's accelerating hard. My trial and error shows that there's a valve on the fire wall that gets a 0V signal which allows the vacuum to reach the heater water valve and not let the hot water to the heater core. It appears to lose that vacuum when I'm accelerating and allows the heater core to get hot. This isn't a complicated system, but I can't figure out what's going on here. Is it the PCV valve?
2. My other issue, which I don't think is related, is that the air to the inside of the cab is either really hot or cold. There's no in-between. I assume this this the temperature actuator, but I haven't dove into it enough.
Any experienced advise you can offer for either of these items will be greatly appreciated.

Here she is. 1998 with 63K miles. We revamped the inside and use it all the time. It's such a fun and nice truck to drive. I just need to get these issues resolved so I can take it on road trips.
TIA

 

[east302]

Is it hot air as in “not conditioned” (incorrect a/c refrigerant charge) or hot as if you switched it to full heat?

The water valve that you mentioned is closed when that solenoid is energized. That happens when the temperature dial is set to the “max” detent. It’s intended to maximize a/c performance, so whether it is open or closed isn’t going to give you a large temperature difference and certainly won’t make you think that someone switched the heat on. In mine, it’s maybe a couple degrees difference between open and closed.

If you’re getting swings between full hot and cold air, that sounds like a blend door issue at the heater core. It’s behind the ashtray and had a silver position indicator dial on it.

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Watch it as the temperature is adjusted. It should rotate smoothly between the raised marks on the housing. Hesitation or a ratcheting sound is usually the result of cracked internal gears.

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[buggs]

Thank you for the feedback. It is hot air as in the water is going through the heater core. The AC works great when it's running at an idle.
I'll take a look at the actuator in response to your notes.
Thanks again.