1996 Dodge Grand Caravan LE AC/Heater Blower, Relay and Resistor Block Problems 101

[TheDevilIKnow]

Thank You HeadlessHorseman1 for your great postings on the HVAC front blower problems. I have a high mileage 96 Grand Voyager with the relay problem for sure as I've replaced the resistor module on the firewall but no change. The classic symptom is that the blower works on all settings then doesn't work. Or will come back on after driving for a while. My problem lies in finding the proper replacement for this relay. Does anyone have the part numbers for the 96 Voyager blower motor relay? I could do a wrecker stop but a used relay seems like good money after bad. The local dealer quoted an astronomical price for this relay that no one in their right mind would purchase for this vehicle. The part number the dealer quoted was 04788010. If there is a cost reference for this or the number is erroneous I would really appreciate a shout back. Regards All!

[jpb53]

If you look at H H's original post again he gave the blower motor relay part# 4638094. If you go here and put in that number it will give you this #4727370AA which is the new part # and costs $7.48 if you buy it at that site.

[TheDevilIKnow]

Originally Posted by jpb53

If you look at H H's original post again he gave the blower motor relay part# 4638094. If you go here and put in that number it will give you this #4727370AA which is the new part # and costs $7.48 if you buy it at that site.

Sorry man, I lost you after you said listen carefully!

If I go where? and put in part number 4638094 I'll be able to buy it at what site?

[jpb53]

Sorry forgot the link!
http://www.moparpartsamerica.com/spl...?siteid=214583

[TheDevilIKnow]

Just a note for folks regarding the heat shrink that HH1 refers to in the posts. My buddy was doing his resistor block connector pigtail splice and he came back with some regular electronics heat shrink that does not have the gummy wax sealer inside. This protects your splice from moisture and oxidation. So when you're on your parts run make sure you get the marine grad heat shrink. This product has a few other names as well that I'm sure someone can add to the posts. Sometimes the devil's in the details.
Regards all!

[Soultear]

Originally Posted by GrandcaravanMan

Hello all,

I have been reading this very informative post and my brain is just frying like an egg. My 2005 GC 3.3 has just lost heat, but, here is the difference.

When I turn my heater on and set the two slides for driver/passenger all the way to full heat, I don't get heat. Now, my fan switch works in all positions, low thru high, and not just in high.The back fan works also.

Although my fan works in all speeds it only blows hot air when I rev the engine up over 3K RPMs. I suspect that that is just engine heat but never the less it's heat.

So, I have everything working as far as the fan blowing in all positions, now does that mean my relays are fine or would the fan/blower still blow if the relay was bad? Does the relay turn the actual HEATING unit on also?

I'm sorry if I'm sounding redundant but it just seems that in my case everything is blowing and working fine but just not blowing hot air.

Could any of this be due to a bad T-Stat?

Thanks,
Jeff

Same problem here. Googled my problem and found this site. Great thread BTW.

I almost have the same problem, but I do have alittle heat coming out the vents, but when I rev up the engine to about 2500-3000 RPM also, the blower motor kicks into high gear (Blows faster) and I get more heat out of the vents.

I have read the whole thread
-resister block for variable fan speed
-Blower Motor Relay for proper amps (40A)

Could my problem be the blower motor relay. My problem sounds like my blower motor not getting enough amps to spin at full RPM. Needs the engine to run at higher rpms to power the blower motor.

My second question would be; what does a AC/heat control module acually do? I read about that module somewheres in this thread also.

Vehicle is a 1994 Grand Voyager 3.8L. Great Vehicle besides dumping the tranny pan every 20000km to change the fluids filter. leant my lesson about these trannys when I had to actually replace my last one, $2500, ouch.

Any ideas would be greatly appreciated.

[PDModel98]

2005 Chrysler Town and Country:
I switched fuse & blower motor relay with the back fan and the back fan still works yet the front fan is still out.
I tried testing the resistor block and the 2 leads going to the blowewr both show hot all the time....any thoughts?

[Hanss]

Originally Posted by Soultear

Same problem here. Googled my problem and found this site. Great thread BTW.

I almost have the same problem, but I do have alittle heat coming out the vents, but when I rev up the engine to about 2500-3000 RPM also, the blower motor kicks into high gear (Blows faster) and I get more heat out of the vents.

I have read the whole thread
-resister block for variable fan speed
-Blower Motor Relay for proper amps (40A)

Could my problem be the blower motor relay. My problem sounds like my blower motor not getting enough amps to spin at full RPM. Needs the engine to run at higher rpms to power the blower motor.

My second question would be; what does a AC/heat control module acually do? I read about that module somewheres in this thread also.

Vehicle is a 1994 Grand Voyager 3.8L. Great Vehicle besides dumping the tranny pan every 20000km to change the fluids filter. leant my lesson about these trannys when I had to actually replace my last one, $2500, ouch.

Any ideas would be greatly appreciated.

**************************************
Hi Guys,

I had this problem about 2 years ago. Unfortunately It has nothing to do with blower motor or thermal resistor and relay. If you have to rev the engine up about 2K-3K RPMs in order to get heated flow - you are facing another problem.
It looks like the problem with your engine cooling system. I belive you don't have enough coolant fluid (Antifreeze). Based on my experience if
you rev the engine up to 3K RPMs you need to add coolant fluid about 1.0L-1.5L more. That means you are losing coolant somewhere. Just check your coolant level.

When you rev your engine up and running the engine on higher RPMs you increasing the pressure inside your cooling system, that means you increasing coolant circulation inside of cooling system, that is why you can get heated air flow on higher RPMs. Because your heater is a part of cooling system.

There are several reasons for coolant losing: coolant pump, engine radiator, heater radiator, coolant system hoses.
You need to perform a "high pressure test" to find out where is a leak and why you are losing coolant. It's possible only on dealership or prof. automotive mechanic.

AC/heat control module just managing air flow whatever it is cold or hot. Cold air flow comming from AC (if it's ON) or from outside, hot air flow coming from engine cooling system. That is a key factor of your problem.

It's Winter time......, so temporarily solution is just check your coolant level and add more coolant up to level mark. But you'll never know how long you can run on it.
It's better to go to prof. mechanic and solve it.

In my case, after "high pressure test" I've found my coolant pump leaking, replaced it. That's it.

All the best.
************************************************** ******

[vandamn]

hi
i am having similar heat related problem with my 2005 caravan. the heater blower does not work. believe cause to be from a dead battery. after charge of battery blower would not turn on. could not find info on calibration sequence for this model. looked in owners manual with no luck. can anyone help me with this.
thanks

[coopdavillage]

you should do what i just did and get rid of it and buy something more reliable

[tempfixit]

vandamn

Read this thread it may help and also do a search using heater fan control calibration and you should see number of threads pertaining to heater problems.

http://www.automotiveforums.com/vbul...ol+calibration

coopdavillage, I assume you upgraded to a recall Toyota.

[HeadlessHorseman1]

In the 5 years that have passed since I originally started this thread, I have not encountered any problems that would require additional troiubleshooting with regard to heater/blower motor issues... here's a new one... after you have replaced your Blower Motor Relay 3 or 4 times, it may be necessary to purchase electronic contact cleanining spray to remove gunk from the socket into which the blower motor relay replacement is inserted. Do it every time you replace the Blower Moter Relay!!!

[HeadlessHorseman1]

There's someting else I wanted to say... don't cheap out on your heating/cooling blower motor issues! Remember, if you replace your Blower Motor and Blower Motor Relay together (which you should do!), your success rate will significantly improve. If your fuse is good and you haven't replaced your Resistor Block after 200,000 miles, do so right away and avoid the winter-induced inconvenience.

Take it from someone who now has 301,000 miles on his Dodge Grand Caravan LE 3.8L!!!

That's right... 301,000 miles.

[HeadlessHorseman1]

Originally Posted by HeadlessHorseman1

There's someting else I wanted to say... don't cheap out on your heating/cooling blower motor issues! Remember, if you replace your Blower Motor and Blower Motor Relay together (which you should do!), your success rate will significantly improve. If your fuse is good and you haven't replaced your Resistor Block after 200,000 miles, do so right away and avoid the winter-induced inconvenience.

Take it from someone who now has 301,000 miles on his Dodge Grand Caravan LE 3.8L!!!

That's right... 301,000 miles.

One more thing... I had to use electrical connection cleaner spray to blow out gunk that has built up in the Blower Motor Relay socket in order for a new relay to work properly. I recommend applying a very light coat of di-electric grease on the relay contacts (with a Q-tip) before inserting a new relay into the newly-cleaned socket.

[RIP]

Still among the best threads on any forum. A big thanks for constant updates HH.