Not heat. Except for idleing.

[Zejokee]

I got a 87 Ranger. 2.9l with 5-speed swap. I do not have any heat when I am driving my truck and the temp. does not go over 100 when I am driving. But if I park the truck and let it idle, the engine warms up and I have good heat. I am baffled why it is doing this. Any ideas?

 

[BRUTUS_T_HOG]

sounds like the thermostat is missing or stuck open

 

[Zejokee]

Possibly. I bought the truck for $200 so... I will check that out tomorrow.
Over the summer I was having problems with it over heating.

 

[srteach]

overheat in summer + no heat in winter (except at idle) = thermostat problems

As simple as that.

 

[martin]

Sounds like a thermostat problem but might also be water pump.

 

[shane96ranger]

Does it have enough antifreeze in it? Low antifreeze could also do what you are describing.