: Overheating, electric fans, and what is this gizmo?



vanagon40
08-09-09, 11:05 PM
I have a 1993 Fleetwood with the 350 V-8. The car really is a “go to church on Sunday” car, with only about 3,000 miles in the past year (130,000 total). I have owned the car a little over two years.

The radiator cap does not fit tightly as the top of the filler neck is slightly distorted. But, before today, the car had not overheated except for when a heater hose broke.

Today the car overheated just as I pulled into my driveway (on the way home from church). The overflow tank was full (and slightly overflowing) and the coolant was boiling. The car was just barely overheated but the TEMP light was on. I observed that when the car was overheated, the right radiator fan was running but the left was not (the car has two electric fans).

I have since discovered that the right fan begins running as soon as the key is turned on and as far as I know never stops running. If I connect the left fan directly to the battery the fan will run in either direction (depending on the polarity) but the fans sounds pretty rough.

I also discovered that a previous owner had connected something (a resistor? diode?) in parallel to the left fan (see photo). The part is labeled as follows: top line “MS”; bottom line “”IN5404GP” (the leading “I” may be a “1” or other slight differences). This was obviously not part of the original design.

http://i207.photobucket.com/albums/bb215/vanagon40/FanConnector005.jpg

Can anyone help me with what is going on here? I do not have a Haynes Book or an electrical diagram. But, it seems to me that neither electrical fan should be running before the engine reaches operating temperature and both fans ought to be running if the car is overheating.

I do have a voltmeter/multimeter, I am knowledgeable about basic electrical wiring, and I am a pretty good trouble shooter. I may need to buy the Haynes to obtain a wiring diagram, but I thought if someone else might be able to figure out what I have or what I need to check, I might be able to fix this without a diagram.

(Although I did not add the resistor or whatever, I am not above hardwiring in extra parts to bypass defective parts. I once had a Volkswagen Vanagon (hence the forum name) that was overheating because the two-stage fan was not operating. Rather than locating the problem, I simply put the high speed stage of the fan on a relay and toggle switch and ran the fan manually. The fan was necessary only when sitting in traffic. I guess I would need to add a temperature gauge to try that solution on the Caddy.)

Thanks in advance for any suggestions.

jayoldschool
08-10-09, 12:24 AM
Can we see a shot of the whole engine compartment? I thought only the 94-96 got dual electrics. Sure you don't have a 94? Where is the rad cap? On the rad, or on a separate tank?

To start, you need to get a properly sealing rad cap on there. If that means replacing the rad, then that's what you have to do...

dirt_cheap_fleetwood
08-10-09, 01:30 AM
Yes, replace the radiator first. The cap needs to fit tightly to hold pressure (around 13-14psi) in the system. Like Jay, I believe the '93 still had a mechanical fan.

RocketFast321
08-10-09, 08:30 PM
93 Should have a fan clutch setup with a back-up fan. With your engine cool spin the fan. Does it almost make a full rotation?

ewill3rd
08-11-09, 06:49 AM
That is a diode, you can tell because of the stripe on one end. Resistors would have colored stripes.
Not sure why he'd put a diode there except to kill a spike which seems odd.

The fan should only rotate one direction unless you are putting voltage and ground to it to make it run backwards, if so... stop it... :lol:

The pressure cap must fit tightly, if the coolant is at normal temps in ambient pressure it will boil. If the cap is loose it can cause that to happen.

vanagon40
08-11-09, 10:15 PM
Okay everyone,

I may not be quite up to par with Mr. Goodwrench, but I know the difference between a mechanical fan (I'm over 50 years old and have worked on more GM 350 engines with clutch fans than I care to admit) and an electrical fan. If you still do not believe me, here are the pics of the engine compartment.

http://i207.photobucket.com/albums/bb215/vanagon40/FanConnectorII001.jpg

http://i207.photobucket.com/albums/bb215/vanagon40/FanConnectorII002.jpg

http://i207.photobucket.com/albums/bb215/vanagon40/FanConnectorII003.jpg

Thank you ewill3rd for confirming that the IN5404GP is a diode (the last time I studied diodes and resistors was at Purdue University in 1980).

Now, back to my original questions (and maybe everyone will claim that the either the engine or VIN sticker has been replaced): shouldn't the right electric fan wait to turn on until the engine is "hot?" Maybe the previous owner wired it to run all the time to keep the engine cooler than designed due to the defective radiator cap/filler neck? Shouldn't the left fan turn on if the engine is overheating? Why would someone splice in a diode in the fan circuit?

Unless someone has some constructive answers, I guess I will need to buy the Haynes manual for the wiring diagram.

Again, thanks in advance for any answers to my questions.

jayoldschool
08-11-09, 10:24 PM
Settle down, no one said you didn't know what you are talking about. It is just that we do know a little bit about these cars. 93 had a mechanical fan. 94 and up got dual electrics, unless it was ordered with the trailer package, which meant a primary mechanical fan, and an electric secondary. I own an example of all three, so if you need a photo, LMK :)

So, what you have is a 93 with a dual electric fan swap from the later years. You still have the original style rad. So, back to the advice. 1, the rad gets replaced. 2, new rad cap. 3, determine how the fans are being controlled and if they are working properly.

Out of curiosity, can you take us a shot of the stickers on the rad support? The belt routing one, and the info sticker...

dirt_cheap_fleetwood
08-11-09, 10:38 PM
:yeah: Someone added the electric fans. Finding out how they are controlled will help solve the problem.

thefleetwoodguy
08-11-09, 10:47 PM
Settle down, no one said you didn't know what you are talking about. It is just that we do know a little bit about these cars. 93 had a mechanical fan. 94 and up got dual electrics, unless it was ordered with the trailer package, which meant a primary mechanical fan, and an electric secondary. I own an example of all three, so if you need a photo, LMK :)

So, what you have is a 93 with a dual electric fan swap from the later years. You still have the original style rad. So, back to the advice. 1, the rad gets replaced. 2, new rad cap. 3, determine how the fans are being controlled and if they are working properly.

Out of curiosity, can you take us a shot of the stickers on the rad support? The belt routing one, and the info sticker...

respectfully disagree, both the 93's I parted had dual elec fans

jayoldschool
08-11-09, 10:57 PM
respectfully disagree, both the 93's I parted had dual elec fans

And that right there, is why this is a great forum. Someone always knows the real story! So, what I said is correct for the B body, not the D body. Looks like Cadillac was first with the dual electrics (like they usually are with the tech before the other divisions get it). I was thinking the fans were standard, though, once I saw the pics. More specifically, the stickers (that I asked for a pic of). That sticker shows the belt routing for the TBI, not the LTI...

RocketFast321
08-11-09, 11:30 PM
Now, back to my original questions (and maybe everyone will claim that the either the engine or VIN sticker has been replaced): shouldn't the right electric fan wait to turn on until the engine is "hot?" Maybe the previous owner wired it to run all the time to keep the engine cooler than designed due to the defective radiator cap/filler neck? Shouldn't the left fan turn on if the engine is overheating? Why would someone splice in a diode in the fan circuit?

Unless someone has some constructive answers, I guess I will need to buy the Haynes manual for the wiring diagram.

Again, thanks in advance for any answers to my questions.

http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?chapterTitle=Wiring+Diagram s&partName=Chassis+Electrical&pageId=0900c1528025ef3d&partId=0900c1528025edee

If that link doesn't work join autozone and you will have free access to all the wiring diagrams.

But the fans will turn on if the a/c is on. Unless it real cool out. Now on my grand am I have a duel fan setup. They run run in pairs, both are on low or high.

But if one fans is running the other should be to, IE the reason it was overheating with a/c. When the other fan is running very carefully take a stick and try to turn the dead one. Is it hard to turn? Even thou it's off is the fan motor hot? Because you might just have a dead motor. You might want to hard wire it to the battery to make sure it's dead. Also are the fleetwood fans two speeds?

Another thing it could but bad fuse, or fan relay. Each fan should have it's own relay.

dirt_cheap_fleetwood
08-12-09, 01:18 AM
respectfully disagree, both the 93's I parted had dual elec fans

Well now I feel stupid. :hide:

ewill3rd
08-12-09, 07:01 AM
Typically one fan will be set to work as the cooling system fan and the other will be used for A/C.
(notice I said typically)
I'd have to review the schematics and see how those are wired, sometimes one is high, one is low, or they are both switched hi and low together but overall GM works fans like this.

Idling normally one fan will come on around 220 F to bring the coolant temp back down and the fan will shut off again around 210 F.
When the A/C is turned on one fan (or both) may come on low speed to keep air flowing over the condenser and when the a/c system high pressure reaches a certain threshold high speed fans or the 2nd "high speed" fan motor is turned on depending of course on how they are wired.

A diode is used on a motor circuit like that to prevent a reverse voltage spike from shooting back through a circuit when a load is turned off.
They could have done that for noise supression or to band aid something else they were trying to fix.

If you want more specific details I can dig in the FSM or on alldata to identify exactly what you should see and when.
Be warned I am really busy right now so I can't promise to set a speed record reporting back.

jayoldschool
08-12-09, 08:56 AM
Idling normally one fan will come on around 220 F to bring the coolant temp back down and the fan will shut off again around 210 F.
When the A/C is turned on one fan (or both) may come on low speed to keep air flowing over the condenser and when the a/c system high pressure reaches a certain threshold high speed fans or the 2nd "high speed" fan motor is turned on depending of course on how they are wired.

This is the way the fans work on the 94-up. If you turn the AC on, the primary fan should come on right away. Additionally (on the 94 up, not sure on the 93), if you unplug the temperature sensor while the car is running, both fans should immediately come on.

ewill3rd
08-12-09, 10:38 AM
Yes that is right, if the ECM doesn't trust the coolant temp sensor it will default to the regular cooling fan on at all times.
Sorry I neglected to mention that.

WMD
08-12-09, 01:24 PM
Another good feature for this era of Fleetwoods and others is that the electric cooling fans are disabled above a set speed as they are not needed at this time above a certain speed.
wmd

RocketFast321
08-12-09, 02:16 PM
Typically one fan will be set to work as the cooling system fan and the other will be used for A/C.
(notice I said typically)
I'd have to review the schematics and see how those are wired, sometimes one is high, one is low, or they are both switched hi and low together but overall GM works fans like this.

Idling normally one fan will come on around 220 F to bring the coolant temp back down and the fan will shut off again around 210 F.
When the A/C is turned on one fan (or both) may come on low speed to keep air flowing over the condenser and when the a/c system high pressure reaches a certain threshold high speed fans or the 2nd "high speed" fan motor is turned on depending of course on how they are wired.

A diode is used on a motor circuit like that to prevent a reverse voltage spike from shooting back through a circuit when a load is turned off.
They could have done that for noise supression or to band aid something else they were trying to fix.

If you want more specific details I can dig in the FSM or on alldata to identify exactly what you should see and when.
Be warned I am really busy right now so I can't promise to set a speed record reporting back.

Yep without a/c on the fans will come come on at 220. I don't have a fleetwood but my cousin has a 96 roadmaster, and both his fans run when the a/c is on. I can't tell if they are in high or low mode. I service manual would help right now.