Engine temperature

[Fred_C]

Recently on a trip to Dallas from Houston, I noticed the engine ran cooler when I turned the dash air on. Is this because the radiator fan increases RPM when the dash air compressor is engaged?

Fred

[Gil_J]

Yes, on most models. Prevost dash air engages the fan in high speed after a short time delay.

On cooler days with dash air on you should see the temperature fluctuate in response to the thermostats cycling.

[Fratto]

I know this is an old thread but I just got our 1999 CC back from the Prevost shop in Fort Worth where they replaced the dash air compressor. We drove it for a couple of hours in the morning with the dash air on and engine temp was 195 or so. Out side temps were probably in the 80's. On the way back later that afternoon, the outside temp was 97 or 98 and in the hills engine temp was pretty close to the 220 tic mark ... call it 215. If we turned off the dash air, it would cool off by about 10 degrees or so pretty quickly. So in our case, it is running much warmer with the dash air on. Has anyone else experienced this?

By the way, Jason with Prevost Fort Worth did a fine job and took great care of us.

[Gil_J]

Your symptoms are pointing to a loose drive belt on the 90 degree gear drive. I'm surprised you didn't get a check engine light.

[Fratto]

They seemed tight to me. I am going to check again now that it is cooler and double check the tension system air pressure. Also will check to see if the fan goes to high speed.
The dash temp gauge may also be reading higher then the DDEC. I need to see if there is a difference between the dash and gauge in the engine bay as well.

I take it that you did not expect it to be running in the 215 range?

[Gil_J]

I can't imagine the air conditioner preventing the fan not to engage the high speed fan clutch setting, especially when it's suppose to do so on it's own after the timer expires.

I certainly would not expect the engine temperature to rise because the the air conditioner clutch is engaged. If Prevost dash air raised the engine temperature with that little compressor can you imagine the impact on engine temperature with the huge 6 cylinder Bus Air compressor.