To Yosemite last year and to the Grand Canyon this year, all from So-Cal, when pulling a hill, the vents stop blowing. Well, depending on the hill, the HVAC will slow, but on a big hill, the HVAC will just stop. Any ideas?? Yellowstone may be next year so getting my HVAC to work won't be a rush. Thanks all.

Do you mean the blower motor stops working or do you mean the AC stops being cold? Many newer vehicles disengage the AC compressor clutch at full or near-full throttle. Might be what you are experiencing.

It's an '87. I'm not sure if it does disengage the A/C, but the A/C doesn't work. I believe the blower motor just stops.

The 350 goes into self protection mode and disengages the compressor to give the motor more hp to pull that hill..... its designed that way

When your over the hill, the load is off the motor & the air comes back on .... yes

Hey there buddy long time no talk . Hope you are doing well. But Yes, once I top the hill and ease up on the throttle the vent does come back on to whatever speed it is set at. But I have just the vents on not the AC since the AC is not working. So the compressor is not doing anything. Normal for a 305?

Does it sound like the blower wheel is rubbing? Too much end play?

Time for a tune up ...I would say your at your weight limit for that motor ... no seriously the fan circuit is tied to the ac ... it kills any draw on the motor to stay running

The blower wheel sounds quite. Seems to be running great. Just blowing sound.

Did every tune up needed/....plugs, wires, cap & rotor, air/fuel filter, trans fluid/filter. I think that's everything for a tune up, right?? If it's suppose to kill the blower motor under a load, then thats a relief for sure. I know it's running normal than. Thanks all for the help again. On to the next thing....turn signal lever replacement.

The #1 censor that the computer goes to is the Coolant Temp censor to see if the motor is running right cause if the motor is hot or tooo cold the comp can adj the fuel & timing. So if your CTC is caked with crap it doesnt give a accurate reading. The "cake crap" is like hard water crust in your home.