If the vacuum is weak it'll do as described. Check your vac pump output and trace the hoses to the vacuum manifold.
AC service possibile conversion
- Thread starter Spun4Fun
- Start date
mu2bdriver
Full Access Member
I only had limited time this morning but I'm getting about 10" of vacuum at various hvac points. I didn't test the brakes yet or try the large hose vacuum pump output. Tired now and will test them tomorrow. I remember when I put the pump on it was pulling 28" all day.
mu2bdriver
Full Access Member
Finally success. I troubleshoot the vacuum down to the line which connects one half of the check valve T to the vacuum reservoir. The pump was pulling good vacuum when tested at the manifold. When I disconnected the aforementioned line and put my thumb over it I could feel the suction immediately and could also feel the air coming from the panel registers. I used a mirror to confirm that the reservoir was mounted to the evaporator housing without any leaks and when I re-attached the line I noticed that there was about 1/16" of exposed male fitting (line wasn't pushed in ALL the way). Pushed it in all the way and it's all good. The diverter door quickly moves from one position to another and all settings work accordingly. So after 18+ months my a/c issue is finally put to bed.
Wvdirtroad
Full Access Member
My truck was converted to 134a by the previous owner and it seems to blow cold really well.
mu2bdriver
Full Access Member
All my thinking and researching on the ac system leaves me with a question: what's the purpose of the vacuum reservoir? Can't that line just be plugged or does it serve a greater purpose in the hvac system?
If memory serves it's a reservoir just for HVAC that keeps a reserve in case the the brake booster pulls too much from the pump/canister supply. There should be a check valve keeping the brakes from drawing off the HVAC side
The quart tomato can reserviour is for Cruise control and a one time braking for the booster, if you would loose the vacuum pump.
I'm assuming the vac reservoir in question is the black plastic box on the evaporator cover, not the soup can
mu2bdriver
Full Access Member
Correct.
