2001 Rear heat is not hot

The Rear heat is not blowing as hot as it use to be. It is warm but it is not heating up the rear of the van. I have smelled antifreeze from time to time. Is there a rear Heater Core?

On models with rear heat and air (which - near as I can tell - is most of them), there is a separate heater core and A/C evaporator in the rear of the van.

Here's a first, simple test: With the van already warm, go outside the van in the rear-left corner, crouch down and look up underneath where the rear heat and A/C unit is. There are four small pipes under there - two for A/C refrigerant supply and return, and two for heat. You'll see how the 4 tubes are mounted in parallel, and snake from the front to the rear of the van.

If the engine coolant loop is working properly, those two pipes should be warm to the touch.

So:

- If the pipes are warm, there's likely something wrong with how airflow is being handled in the rear unit. Further diagnosis happens at the rear of the van.

- If the pipes are *not* warm, there's something likely wrong in the engine coolant system that's blocking the warm fluid from getting to the rear unit. Further diagnosis happens under the hood at the front of the van.

I'll also ask my first follow-up question: Has the engine coolant system been serviced regularly during the life of the van? Flushing and filling the coolant system frequently is a great way to avoid blockages and other problems in the system later on.

I have had it serviced a couple times in the 4 years I have owned it. I think it is the rear heater core that is bad. I checked the lines and the inlet line is very hot but the outlet line is warm.

It could be partially clogged. Try backflushing it with a garden hose.