Community Forums

wracinti · 06-25-2022, 09:34 AM

Saw a post somewhere, can't remember, that if the dash AC is on it will automatically kick on the engine fan to low speed.Is that correct? Would that help engine cooling going down the road?

1JetDoc · 06-25-2022, 09:45 AM

Quote:

Originally Posted by wracinti

Saw a post somewhere, can't remember, that if the dash AC is on it will automatically kick on the engine fan to low speed.Is that correct? Would that help engine cooling going down the road?

Engine fans in most modern vehicles are temperature controlled. The fan kicks on when the coolant temp in the radiator reaches a certain pre-set level.

While running the vehicle's AC system DOES make the engine work a bit harder and may raise the coolant temp by a few degrees, I've never seen one that automatically turns the fan on just because the AC is switched on.

wracinti · 06-25-2022, 09:55 AM

Ok Thanks

Skip426 · 06-25-2022, 10:02 AM

The fan cycle can vary by , chassis manufacturer and radiator placement .

Side rad and rear rad chassis are going to have different cycles .

My side rad hydraulic fan is always turning at low speed , and cycles to high with temp AND A/C compressor operation , something I consider odd because the A/C condenser is not in the cooling stack and has it's own electric fan .

The side rad cooling fan on high , with the compressor , is a major contributor to the Freightliner " dust storm " issue .

redbaron73 · 06-25-2022, 10:05 AM

My 2013 and 2019 Freightliner Dutch stars both would lock fan to high speed as soon as the AC compressor was enabled. Remained for 3 minutes after ac compressor was disabled.

My 2022 Spartan does not behave the same. The AC compressor does not demand high speed fan just by being enabled.

Dutch Star Don · 06-25-2022, 10:15 AM

At least from 2014 forward, on a Freightliner, the engine fan goes to HIGH when the A/C is on.

dav-cle · 06-25-2022, 10:54 AM

Quote:

Originally Posted by Dutch Star Don

At least from 2014 forward, on a Freightliner, the engine fan goes to HIGH when the A/C is on.

My 2011 MADP does the same, and thanks to you I remedied the Freightliner dust storm.

sdhexpert · 06-25-2022, 03:45 PM

Quote:

Originally Posted by Dutch Star Don

At least from 2014 forward, on a Freightliner, the engine fan goes to HIGH when the A/C is on.

This behavior is troublesome. Came into a dusty gravel campground recently. Had the dash AC on in the coach - took about 5 minutes for the cloud to settle. People next to us were just shaking their heads. These side fans can really move some air! Coach needed a good wash after that one campground - really need to stay on the pavement.

Dutch Star Don · 06-25-2022, 04:21 PM

Quote:

Originally Posted by sdhexpert

This behavior is troublesome. Came into a dusty gravel campground recently. Had the dash AC on in the coach - took about 5 minutes for the cloud to settle. People next to us were just shaking their heads. These side fans can really move some air! Coach needed a good wash after that one campground - really need to stay on the pavement.

I make it a habit to turn the dash A/C off if the campground has dirt roads. We once blasted a campground near Seattle when we first got our 2014 DS. We drove down a dirt road and I could see people running for cover.

tqqest · 06-25-2022, 08:31 PM

With the Cummins PowerSpec software and an interface device, you can adjust whether the engine fan comes on when the A/C is turned on, or how many seconds it stays on if it is enabled. You can also choose whether or not the fan comes on with engine braking to enhance engine braking ability.
I have the engine fan setting disabled for both on my motorhome.

Dutch Star Don · 06-25-2022, 09:55 PM

Quote:

Originally Posted by tqqest

With the Cummins PowerSpec software and an interface device, you can adjust whether the engine fan comes on when the A/C is turned on, or how many seconds it stays on if it is enabled. You can also choose whether or not the fan comes on with engine braking to enhance engine braking ability.
I have the engine fan setting disabled for both on my motorhome.

That's nice to know. I feel that the fan comes on needlessly with the A/C on and robs fuel mileage.

Skip426 · 06-26-2022, 07:30 AM

Quote:

Originally Posted by Dutch Star Don

That's nice to know. I feel that the fan comes on needlessly with the A/C on and robs fuel mileage.

Being a vintage coach , on F/L with a Cat engine , looks like I have to do some investigation into the signal connection between the A/C control, compressor clutch cycle , the ECM and the rad fan control module .
With only 300 HP , I don't have any to spare ; given the hydraulic fan power draw; that always happens at the worst times; usually passing a semi on the Tehachapi or Siskiyou.

tqqest · 06-26-2022, 07:41 PM

Quote:

Originally Posted by Dutch Star Don

That's nice to know. I feel that the fan comes on needlessly with the A/C on and robs fuel mileage.

Agree with you there! That’s why I disabled that setting on mine. Freightliner was charging me $100 a pop for each parameter change I made, plus I had to go to them. Makes it really tough to tryout new settings. That’s why I ended up downloading the Cummins PowerSpec software, which is free, (you just contact them as an owner to get the software license for free each year.) Then I bought the plug-in interface device, and now I can change any of the parameters at will and try different things. I’ve altered many of the parameters on all 3 of my diesel motorhomes.