Radiator cooling fan does not come on while A/C is running

Tiny
WILLIAM DOERFLER
  • MEMBER
  • 2008 CHRYSLER TOWN AND COUNTRY
  • 4.0L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 270,000 MILES
Greetings. I have the van listed above Limited. When I'm turn on the A/C in the cab, I get meager cool air from the vents after a few seconds while travelling at highway speeds. If I slow down to city speeds or have it stopped and idling, it will lose all cold air.

I've had this problem for awhile now and have noted that I never hear the radiator cooling fan come on to high speed with the A/C running. Previous vehicles I've owned have all had the rad fan come on high speed with the A/C running. This van is not doing that and it's getting annoying.

Just today I unplugged the coolant temp sensor and started the van. The fan came on to high speed a few seconds after the engine was started and stayed there.

Shut it off, reconnected the sensor, started it again, and it was idling quiet like it normally does. Turned on the A/C and then stood around having a smoke while I waited for the rad fan to turn on. After 10 minutes it still wasn't on so I took the van out on the road.

On the county road, at speed, I get meager cool air from the vents as I've come to expect from it. When I turn back into the neighborhood and slow down the cool air all but disappears again.

Pulled into the driveway and left it idle. Engine was up to normal operating temp (needle in the middle of the gauge or slightly below) and left it idle for a bit. Low speed fan kicked on for less than a minute and shut off again. A/C was on the whole time and the temperature inside the van went up instead of down as it was blowing hot air from the vents.

Took it back out on the country road (55 MPH) and I was getting cooler air from the vents again after about 20 seconds. Turned around came back home and parked it at idle in the driveway and it had already started blowing warm air from the vents again.

Just for giggles I shut it off, disconnected the coolant temp sensor again (ouch) and started it back up. Fan came on high speed a few seconds after it was running at idle. Went for a drive and it was blowing hot air out of the vents. I'm guessing maybe its a safety thing with the computer trying to bleed off heat any way it can since it can't see the coolant temperature. Having the A/C on or off didn't matter it was hot for the 5 minutes I was driving.

Stopped in a parking lot, turned it off, reconnected the sensor, started it again. Radiator fan was off, A/C was on, drove back home and was greeted with cooler air from the vents about 20 seconds after getting up to highway speed again.

I was hoping that disconnecting the sensor would put the fans on the whole time and allow me to verify that the A/C was actually working by blowing cold (not cool) air.

I forgot to stick a thermometer in the vent before I started all this, but in the past it would be somewhere between 70 and 80F when cruising down the Interstate, and go up to 100F or more when driving city or neighborhood streets.

It seems to me that the fan not running at high speed is the problem. I know the fan and relays and control circuit work because when I disconnected the temperature sensor it put the fan to high speed right away, reconnecting it stopped that.

I've had the A/C checked earlier this year at it was still charged from when I had it checked last fall, so it isn't leaking refrigerant. I haven't checked it since then but assume if it nots leaking then it's still charged. The fact that if I gun the engine to get up to speed to enter the freeway and it tries to blow cold air for those few seconds tells me the compressor is working.

I'm guessing that the radiator fan not running at all with the A/C turned on is the culprit. I'm looking to confirm that or follow another viable alternative to diagnose this problem so I can fix it or get it fixed. Any help is appreciated.

I've worked on cars plenty in the past, but never professionally. I was a diesel mechanic in the military, and I spent a few years working on transit busses after getting my discharge. I'm no stranger to tools or getting dirty, and I'm also a pretty technical guy working my job as an IT professional for the last 20+ years. I've got wrenches and screwdrivers and air tools and a gauge set and a multimeter among other things. I replaced fuel injectors, wheel bearings, shocks and struts, alternators, lifter rods, and various electrical bits on passenger cars and trucks over the last couple decades (I have the tools, so all the friends come to use my garage, and my tools, and me).

With all that, I have to say I'm at a bit of a loss with this specific problem.

Also, sorry for the long-winded explanation here. I've found its better to be reasonably specific when describing these kinds of problems.
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Wednesday, August 11th, 2021 AT 2:25 PM

12 Replies

Tiny
WILLIAM DOERFLER
  • MEMBER
Did another test last night because something was bothering me. Unplugged the coolant temperature sensor again and went for a drive (fan was running at high speed the entire time). At 40 MPH and about 1,350 RPM, the vents blew slightly cool air (a few degrees cooler than the 86F outside temperature). From a stop, if I gun the engine to get up to speed, at 4,500 RPMs it starts to blow cold air. That doesn't last however as the transmission shifts to the next gear and the RPM comes back down. Sitting at a stop it'll blow cool for a few seconds then warm up to the ambient temperature again. It was idling at 1,000 RPMs with the sensor disconnected (otherwise 650 to 700 RPMs normally).

The air from the vents never stayed cold long enough for the thermometer I stuck in there to register a real change. The cool air coming from the vents at speed was between 75 and 80F. Didn't really matter if it was on Recirculation or not, or if I had the rear cabin A/C going or not.

Plugged the sensor back in, and the cool air was somewhat less cool at a speed. This was expected.

I know the system doesn't (or didn't) leak as it was vacuum tested late last year and it held vacuum fine for an hour. I'm assuming it is properly charged but I didn't fill it so I really can't say, and I don't know what pressures I should be seeing on the high and low sides to know if it is ( have a gauge manifold and can check it). But based on how its acting I'm guessing its either a low charge or a bad compressor? The compressor does engage and disengage like it should, but where on most vehicles you get an audible click or clunk when the compressor comes on mine will only show a momentary decrease in engine RPM for half a second (no sound from the compressor kicking in). Or possibly it has too much oil in it? I know the guy that filled it last "gave it a shot of oil" so maybe it has too much in the system? Again I don't know as A/C isn't one of my stronger subjects. I know most of the parts and what they do for an A/C system and generally how it works, but that's about as far as my A/C knowledge goes.
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Thursday, August 12th, 2021 AT 5:28 AM
Tiny
KASEKENNY
  • EXPERT
I think we need to start from the very beginning because you are making a lot of assumptions and I think that is taking us down the wrong path.

Unplugging the ECT sensor will cause the fan to come on but does not definitely tell us if there is an AC issue.

So I would suggest we stay with an A/C issue and then get that blowing cold and figure out if there is a fan issue. Basically the fan should be on high when the A/C is on except when the TIPM feels it is not needed. You do not have a dual fan set up so the fan speed will vary depending on need.

So even though the system was check a while ago and had no leaks does not mean it didn't start leaking recently.

Let's start with checking the pressure of the high and low side of the system while the engine is off and with the A/C on.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

If you don't have a gauge set then you can rent them from most part stores.

Just hook them up and let us know what you find. Feel free to get a video of the pressures and we can go from there.

Until we know what the pressure is, we are just guessing at the issues.

Thanks
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Thursday, August 12th, 2021 AT 2:59 PM
Tiny
WILLIAM DOERFLER
  • MEMBER
Engine off, A/C on (key on to do that), pressure lo/hi is 85/85.

Sorry for the delay, I was away with family.
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Sunday, August 15th, 2021 AT 6:13 PM
Tiny
WILLIAM DOERFLER
  • MEMBER
For giggles, engine on and A/C on max, lo/hi is 77/142. Radiator fan is not engaged, vehicle hasn't been running at all for the last two days.
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Sunday, August 15th, 2021 AT 6:17 PM
Tiny
WILLIAM DOERFLER
  • MEMBER
In anticipation of the next request. After idling for 10 minutes with A/C on max cool, pressure lo/hi is 96/135. A/C condenser in front of the radiator is only warm to the touch, and the radiator fan hasn't yet turned on. Ambient air temperature during all of this is 75 degrees Fahrenheit.
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Sunday, August 15th, 2021 AT 6:31 PM
Tiny
KASEKENNY
  • EXPERT
Okay. Take a look at this chart. At 75 degrees you low side is high and the high side is low.

That is almost always a compressor that is failing. Even without the fan running the pressure should be correct.

However, we can prove out that the fan is not the issue by checking the pressure with the engine and A/C on then jump the fan on so that it is spinning on high. It may cause the pressure to change slightly but I doubt it will cause it to come into line.

You can just remove the relay and jump voltage to pin 87. Wiring diagram shown below.

Also, do you have a single or dual fan? You should have dual fans but it appears there is a chance you have a single fan.

If so, the fan issue may just be a TIPM issue. However, I still think there are two issues but let's rule out the fan being related to the AC by jumping it and checking the pressures.

Let me know if you have questions.

Thanks
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Sunday, August 15th, 2021 AT 7:51 PM
Tiny
WILLIAM DOERFLER
  • MEMBER
This is a single fan vehicle. I'll try to check it out this evening after I'm home from work.
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Monday, August 16th, 2021 AT 6:45 AM
Tiny
KASEKENNY
  • EXPERT
Okay. That makes sense. So that helps tremendously. That fan is only going to come on when it is commanded and that does not mean when the A/C is on. Two fan systems will have the condenser fan on at all times the A/C is on and then the radiator when it needs it. Since you only have one, that is turned on when the PCM sees the need.

There could be an issue with the fan but that is not causing the A/C issue.

If it were me, I would be looking to replace the compressor at this point. However, if you want to jump the fan on to confirm this then that will help with confidence that the compressor is the issue.

Thanks for that info.
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Monday, August 16th, 2021 AT 10:47 AM
Tiny
WILLIAM DOERFLER
  • MEMBER
Sorry! Was out of town for a few days for a wedding.

Radiator fan running didn't change anything, still slightly cool maybe at idle and only tries to blow cold air after the RPM goes high. I suspected the compressor based on how it was behaving, but neither shop thought that was the case. I guess I'll need to find another shop to do the work for me since I don't have anything to store refrigerant in.

Thank you for the assistance in helping me nail this problem down, it is appreciated.
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Wednesday, August 25th, 2021 AT 6:20 AM
Tiny
KASEKENNY
  • EXPERT
Yep. That is great confirmation. Thanks for coming back to update us.

Here are a few helpful documents that will help with this if you want to do the job yourself:

https://www.2carpros.com/articles/replace-air-conditioner-compressor

Plus here is the info from the manual. Please let us know if you have other questions but thanks for using 2CarPros.

If you care to help spread the word on the site, leave a review at this site. Clearly not necessary but we appreciate it.

https://www.sitejabber.com/reviews/2carpros.com

Thanks
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Wednesday, August 25th, 2021 AT 4:09 PM
Tiny
WILLIAM DOERFLER
  • MEMBER
Not doing it myself as I don't have anywhere to pump refrigerant to/into. Besides I don't mind paying someone to do the job right and well the first time around. Wanted to confirm this before I went to a shop (and perhaps the dealer shop again) to price out the replacement, especially since a couple shops have already said it was a different problem. One shop said I had to replace the entire A/C system due to age because that's why it didn't work well. Thanks again for taking the time to help me confirm what I suspected.
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Thursday, August 26th, 2021 AT 4:53 AM
Tiny
KASEKENNY
  • EXPERT
Got it. Thanks again for the info and sticking with us. If there are any developments that you feel are worth sharing feel free to come back and post them on this link.

Thanks for using 2CarPros.
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Thursday, August 26th, 2021 AT 5:50 PM

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