90xj 4.0l cruise control and heater inop

Are the cruise and heater valve tied together on the same vacume circuit? Anybody have a diagram ? I think I have a leak the cruise wont stay set and it takes awhile to get interior heat ,seems like the heater valve is not opening all the way.The valve is not froze up .It seems that stuff ties into the canister behind the front bumper ? thanks for any help.

The cruise runs off the vac canister behind the bumper as does the heater which diverts it to the heater valve which diverts hot coolant through the heater core. However, the 4wd is also run off the vac canister. Check the vac lines to and from the vac canister.

A friend of mine had heat only from the defrost and it turned out that one of the tabs on the vac canister broke off leaving a big hole in the canister itself.

Good luck finding the problem.

I'm about 80% sure that vacumn is applied to send coolant through the heater core, meaning a vac leak won't result in poor heat. The vac line to mine was broken and I still had heat. Easy enough to pop the hood and see if the vavle is fully open, though. The heater core probably just needs a good back flushing.

Just looked at a 88 FSM and it confirms this. Vacumn is applied to close the vac valve, and the chart shows it being closed for a/c and open for heat.