That's what I was wondering. It could be he has a bad vacuum check valve.The fan stops or does it start blowing out defrost?
Did you check to see if this check valve is any good? How about the one up against the firewall that goes to the vacuum ball and A/C system?Have vacuum to the purple line on HVAC controller. I don’t hear any leaks if I go through any settings. Have vacuum to the canister center line. Vacuum line to the ball was not on very far and could use a replacing as it is somewhat rotted. I don’t have an EGR see pics of current setup. Checked over all other hard plastic vacuum lines but did not find anything. Going to replace ball vac line and see if that fixes it.
Looking closer at your picture....it looks like you have the vacuum check valve in backwards.
I'm taking my comment back! The picture you posted is from over the top of the engine from the right side. It made everything look backwards. OOPS!Looking closer at your picture....it looks like you have the vacuum check valve in backwards.