Gmc Jimmy 1997 Heat intermittently working

[fathead031984]

So here it is i followed the wonderful thread on how to get the front axle working and chased down the issue and finally got my 4x4 to work. Now not sure whaT I DID but my heat is working intermittently and engine seems to be getting cool intermittently while driving . did i unplug a vacuum going through the system. the heat and car never overheated until i started troubleshooting this vacuum 4x4 issue any input would be great.. oh yeah in the middle of driving the engine cools down to normal operating temp then the heat works until it stats getting hot again

 

[fathead031984]

Engine Overheating after tinkering with vacuum lines

Ok sorry if I wasn't specific enough . So the engine started overheating after I changed my vacuum lines. Not sure wher to go . All the gates work from the selector on the dash . And can hear it change from hot to cold when selected. The truck starts to over heat and as soon as this happens my interior heat stops working . Checked and found my coolant resivoir low really low so I filled it and still no change. I can see the engine temp now fluctuate while driving. Like I said everything in this system worked perfectly until I started ripping out vacuum lines. Could I have pulled off one related to cooling system or got air inthe system by removing the battery to get at my4x4 actuator any help will be great

 

[Molson02536]

Ok sorry if I wasn't specific enough . So the engine started overheating after I changed my vacuum lines. Not sure wher to go . All the gates work from the selector on the dash . And can hear it change from hot to cold when selected. The truck starts to over heat and as soon as this happens my interior heat stops working . Checked and found my coolant resivoir low really low so I filled it and still no change. I can see the engine temp now fluctuate while driving. Like I said everything in this system worked perfectly until I started ripping out vacuum lines. Could I have pulled off one related to cooling system or got air inthe system by removing the battery to get at my4x4 actuator any help will be great

Start with the simple and replace your thermostat, it sounds like it's sticking and will need to be replace. Also this would be a good time to flush out the coolant with Preston Coolant flush and make sure you have the Dex-cool mixed 50/50 with water/coolant.

Good luck and keep us posted.

 

[fathead031984]

Found heating problem

Replaced thermostat and continued filling and letting the
Motor breath through the radiator cap . Heat can now toast a burrito. Thx you guys are awesome and continue to save me lots of cheese!!!