Intermittent heat with no temperature control?

First and foremost let me say to anyone who might consider buying this vehicle. Don’t. It’s been a giant pain. The way this vehicle is designed is odd and makes easy things difficult.
Anyhow, I bought this van used in the spring. I get hot very easily and never thought to check the heater, just the air.
So the air conditioner works great. Sometimes too great meaning it just has the one setting. COLD
If I adjust the temperate knob nothing happens.
I have to turn the knob fully to heat and wait a while for any warm air to spill out.
The same is true in the other way around.
Frequently I can not get the car to blow warm air when idling. Considering the amount of time I spend a day in my idling vehicle and November around the corner this is becoming an issue.
What is likely to be the issue here?
I have been able to get warm air when idling, but it isn’t the norm.
Sometimes even when driving long periods I still have trouble getting it to stop blowing cold.
There is no real consistency to the behavior only levels of probability.
Also worth noting, the engine remains at a good temp. It never runs hot or cold

What have you done to solve this . You bought a used vehicle but a good shop should be able to fix this . It sounds like you are not able to fix it yourself so ask coworkers and friends for a good shop.

A shop should be able to diagnose the problem without much difficulty. Likely the HVAC blend door, actuators fail on many brands. Less likely but possible, heater core is partially clogged.
As a used vehicle, you have no way of knowing how, if ever, the cooling system was maintained.


Check the coolant level, if the engine is low on coolant the heater won’t operate.


Does it have a mechanical knob to adjust the heat or is it one of the more fancy electronically controlled climate control systems?

All good ideas above. If those don’t pan out, try flushing and refilling the cooling system w/fresh coolant. You might want to backflush the heater core at the same time. The other thing to check is the valve which meters the amount of coolant going to the heater core. Sometimes those will clog up. Double check that valve passes liquid-flow freely, and reduces the flow in increments as you turn down the temperature setting. Replace the thermostat and radiator cap too, if that hasn’t been done in a while.