Fan Issue??

[cayman]

I've looked around using the search but couldn't find the answers I'm looking for sooooo..........

1998 RT/10
Roe Supercharger
Roe Thermostat
Never had these issues before

So I'm running along and not really paying attention to the gages when I pull up to a stop and looked down. The coolant gage was approaching the second mark before 250! I noticed the fan wasn't running. Once I got rolling the temp came down so I know the water pump was working, and the thermostat was open. Pulled into my shop and ran the temp up in idle and I ended up turning the ac on to get the fan to run. It did. So that told me the fan works. I shut the ac off and let the temp creep back up. The fan finally did turn on and the temp gradually came back down.
I thought these systems has a two speed fan that comes on low during a certain temp range and kicks in high when the temp gets beyond that. I've only noticed one speed when the fan does kicks on.
The other thing is I've been reading that there are separate sensors for the fan, gage and pcm but according to the service manual I have, there is only one sensor in the driver's side head that supplies the signal to the pcm which in turn, operates the fan relays and the gage. If this isn't true, then where are these other sensors?
What's the best way to check the high/low speed of the fan? Why would the fan kick on when the AC is on but not with it off and the temp is in the range where the fan is suppose to kick on? The gage seems to be operating correctly.

 

[dave6666]

Get a new sensor. $50 from Tator's Dodge or so. About that. Call the Chuckster for details.

The AC fan mode is not dependent on the sensor.

You can also pull your relays and check the socket and terminals. Check the connectors at the sensor and fan. Wiggle and inspect kind of stuff. But the sensors do go bad.

 

[cayman]

Thanks. I read the manual in detail and confirmed that one sensor does it all. The relays appear to be under the blower motor so I'll check those when I get a chance. Can the dealer use their diagnostic tool to manually signal the PCM to turn the fan on in both speeds? That would confirm the relay, fan and associated wiring checks out, leaving the sensor to suspect, wouldn't it?

 

[Steve-Indy]

If your 98 manual is like mine, that location for the relays is wrong...a left over Gen I description and photo. Gen II fan relays are located in a small square box right next to the red positive jumper terminal on the driver's side...just in front on the large fuse/relay box. There are 4 relay sockets,3 are used...high & low speed fan relays, one starter relay.

 

[cayman]

Thanks for the headsup on that. I was getting ready to pull the blower housing.

 

[whitebluevipe]

i have been havivng the same problem with my gen 1. i gets super hot and the fan doesn't kick on. i know the fan works because when i shut the car off my roe after run fan kit kicks on.

 

[Steve-Indy]

By the way, if this a ''first-time-out-of-the-blue'' type thing...check coolant and oil level to be sure that you are not mixing them due to a contained failure of the timing chain cover gasket...not an unheard situation on a 96-98 Gen II.

 

[cayman]

The only thing I did was change out the oil pan but I don't see how that would have anything to do with this. Also, I've already had to pull the timing chain cover and replace the gasket because of an external oil leak issue after putting the ROE SC on. That was about 1,000 miles ago. No issues there.

 

[Steve-Indy]

So much for that gasket theory!!