Ran my 299c a couple weeks ago in freezing temperature and I noticed the coolant temperature was pegged all the way hot, even though it was a cold start. The heater also only reached lukewarm when the engine warmed up. Got it out again today and have the same symptoms- temperature sensor pegged hot on cold startup. It doesn't change after running it for a while and heater only got lukewarm on the hottest setting. The sensor itself seems to work as the needle drops back to cold when the engine is off. Any ideas on how to troubleshoot it?
Forgot ro mention, I checked coolant level and it is full.
JSP or NMP machine? Need to find information. Do you have a non-contact infra-red thermometer that you can use to check temperatures of various coolant hoses.?
Hi Nige! Serial #: CAT0299CAJSP02200 Yes I do have a non contact thermometer.
In that case can you shoot the temps of the engine thermostat housing and the return coolant hose back to the engine when it is fully warmed up and post your results. Locate the coolant temp sensor #5 and unplug it. What happens to the coolant temp reading.? Test the black wire has good continuity to machine frame ground.
Took me a while to get back to the machine, but I have good news. Thanks to the help above from Nige, I found the temp sensor and immediately knew what was wrong. The connector had somehow come unclipped and had slipped out. Plugging it back in and the temp gauge immediately read normal, radiator fan slowed and cab heat started working again. Big relief it wasn't a bigger issue. Thanks as always for a great community and Nige for the guidance!!