HVAC
HVAC - Heating, Ventilation, Air Conditioning
The most common HVAC issue with our vans seems to be the vacuum control of the heating valves and air diverters.
Make sure to check out the HVAC Airflow page.
If your heater hoses/cores aren't getting hot, check:
Engine is up to normal operating temperature
Coolant level and that there aren't air bubbles in the system
Proper vacuum supply, cracked/disintegrated hoses are not uncommon
Ensure control valves aren't stuck/clogged
Flush/replace clogged heater core(s)
The heater water control/bypass valves operate off of vacuum and electric.
If you are going to be changing hoses or working near/with the heater control valves, it's best to order them ahead of time as it's extremely common for them to be brittle and crack simply by looking at them. Plan ahead when it comes to these valves, there are a few different setups, but the below image covers a common setup for the 4 and 6 port valves. if you are removing the rear heat, then you can use the 4 port valve in place of the 6 port valve and don't install the rear bypass valve.