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Cooling fans only working on low speed


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Hello All, im new on this forum so please please some one help me out here, ill describe my problem:

I own a 1996 eldo, my cooling fans only come up on low speed and prior to this sunday the cooling fans did come on at full speed as soon as i turn the A/C on so now i have an overheating problem no mether how hot the car is the fans will only run at low speed, i have done the following:

1.- Chet the 3 relays between the cooling fans

R= The relay are working fine.

2.- Check the maxi fuse

R= The maxi fue is A ok

3.- Check the A/C compresor relay.

R= The A/C compresor is working just fine

4.- Check all of the fuses on from under the hood.

R= All fuses are fine.

So what sould i do next ??

Any help spmeone please!!!!!

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How high is the temperature getting?

You should check for trouble codes. Click on this link and it will tell you how if you don't already know.

http://www.caddyinfo.com/readingcodes.html

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How high is the temperature getting?

You should check for trouble codes. Click on this link and it will tell you how if you don't already know.

http://www.caddyinfo.com/readingcodes.html

It gets 2nd line after the half, i know how to pull codes and i dont get any AC codes

Help please

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How high is the temperature getting?

You should check for trouble codes. Click on this link and it will tell you how if you don't already know.

http://www.caddyinfo.com/readingcodes.html

It gets 2nd line after the half, i know how to pull codes and i dont get any AC codes

Help please

You say you dont get any AC codes, the fans dont set AC codes, they set P codes do you have any P codes, see this list

P0480 - Cooling Fan Relay 1 Control Circuit

P0481 - Cooling Fan Relay 2 Control Circuit

P0482 - Cooling Fan 3 Control Circuit Malfunction

P0483 - Cooling Fan Rationality Check Malfunction

P0484 - Cooling Fan Circuit Over Current

P0485 - Cooling Fan Power/Ground Circuit Malfunction

Also do you have any COOLANT TEMP SENSOR codes, its possible that the PCM thinks your engine is cool and not invoking HIGH fans

What codes do you have

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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How high is the temperature getting?

You should check for trouble codes. Click on this link and it will tell you how if you don't already know.

http://www.caddyinfo.com/readingcodes.html

It gets 2nd line after the half, i know how to pull codes and i dont get any AC codes

Help please

Just because it's not an AC code doesn't mean it couldn't be relevant to the problem you are having, so if there are any codes at all, you should post them. It helps us to help you.

You said you checked the 3 relays between the cooling fans and that they were working fine. How did you check them? You can't tell just by visual inspection whether or not they are working properly.

big4870885.jpg

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Here is a cooling fan schematic

CoolingFan2.jpg

CoolingFanPage1.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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How high is the temperature getting?

You should check for trouble codes. Click on this link and it will tell you how if you don't already know.

http://www.caddyinfo.com/readingcodes.html

It gets 2nd line after the half, i know how to pull codes and i dont get any AC codes

Help please

Just because it's not an AC code doesn't mean it couldn't be relevant to the problem you are having, so if there are any codes at all, you should post them. It helps us to help you.

You said you checked the 3 relays between the cooling fans and that they were working fine. How did you check them? You can't tell just by visual inspection whether or not they are working properly.

I unplug them and check them with a voltmeter on normally open, relay coil, and coil open im an electronic engineer so I did test the relays properly.

Ok so ill check the codes and post them thanks everyone for the prompt support.

Regards

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How high is the temperature getting?

You should check for trouble codes. Click on this link and it will tell you how if you don't already know.

http://www.caddyinfo.com/readingcodes.html

It gets 2nd line after the half, i know how to pull codes and i dont get any AC codes

Help please

You say you dont get any AC codes, the fans dont set AC codes, they set P codes do you have any P codes, see this list

P0480 - Cooling Fan Relay 1 Control Circuit

P0481 - Cooling Fan Relay 2 Control Circuit

P0482 - Cooling Fan 3 Control Circuit Malfunction

P0483 - Cooling Fan Rationality Check Malfunction

P0484 - Cooling Fan Circuit Over Current

P0485 - Cooling Fan Power/Ground Circuit Malfunction

Also do you have any COOLANT TEMP SENSOR codes, its possible that the PCM thinks your engine is cool and not invoking HIGH fans

What codes do you have

I was thinking Coolant temp sensor too. Couldn't that be ruled out by PCM overriding the fans to see if they will turn on to high speed without the coolant temp sensor "telling" them to?

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You can't easily override the system on OBD2s cars that began in 96

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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You can't easily override the system on OBD2s cars that began in 96

I must have misread the post. I thought it was a 95. My mistake.

I'm not very familiar with OBD2, does it have the PCM data display function like the OBD1? Or would you actually need a diagnostic tool to hook up to it? I know there's a way to monitor the coolant temp sensor that way.

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You can't easily override the system on OBD2s cars that began in 96

How can i do that the codes i get are:

RF 2560 HISTORY

PC0603 HISTORY

PC1026 HISTORY

PC1634 HISTORY

PC1552 HISTORY

AC1312 HISTORY

TC0077 HISTORY

NO IPC CODES

NO CCP CODES

PCM?

P0603 - Control Module Long Term Memory Reset

PC1026 - cant find this, could you mean B1026 - Driver Deployment Loop Open

P1634 - Ignition 1 Switch Circuit

PC1552 - cant find this, could you mean B1552 - Keep Alive Memory (KAM) Error

AC1312 - cant find this, could you mean B1312 - High Side Temp Sensor Open Circuit

I believe your AC1312 is stopping your compressor from engaging, and may be impacting your high fan from coming on with the AC switch. Check to see if your AC clutch is engaging with the AC on. Ill have a look at the manual to see what an AC1312 does when it sets and what circuits it impacts and refresh my memory as to how the fans work with the AC off.

If that it is true that your fans are not coming on because of the C1312 code, your temp gage will have wider swings because they turn on at about 228 and turn off at 217, if you are not familiar with the wider range it can appear that something is wrong. Another possibility is that below a certain outside temperature the fans do not run with the AC switch on.

What you should try is, the next time your TEMP gets high lift the hood and see if the fans go to high, they may only go to high when the temp hits 227/228, do you have a service manual?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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You can't easily override the system on OBD2s cars that began in 96

How can i do that the codes i get are:

RF 2560 HISTORY

PC0603 HISTORY

PC1026 HISTORY

PC1634 HISTORY

PC1552 HISTORY

AC1312 HISTORY

TC0077 HISTORY

NO IPC CODES

NO CCP CODES

PCM?

P0603 - Control Module Long Term Memory Reset

PC1026 - cant find this, could you mean B1026 - Driver Deployment Loop Open

P1634 - Ignition 1 Switch Circuit

PC1552 - cant find this, could you mean B1552 - Keep Alive Memory (KAM) Error

AC1312 - cant find this, could you mean B1312 - High Side Temp Sensor Open Circuit

I believe your AC1312 is stopping your compressor from engaging, and may be impacting your high fan from coming on with the AC switch. Check to see if your AC clutch is engaging with the AC on. Ill have a look at the manual to see what an AC1312 does when it sets and what circuits it impacts and refresh my memory as to how the fans work with the AC off.

If that it is true that your fans are not coming on because of the C1312 code, your temp gage will have wider swings because they turn on at about 228 and turn off at 217, if you are not familiar with the wider range it can appear that something is wrong. Another possibility is that below a certain outside temperature the fans do not run with the AC switch on.

What you should try is, the next time your TEMP gets high lift the hood and see if the fans go to high, they may only go to high when the temp hits 227/228, do you have a service manual?

Hello i have open the hood and see if the fans come on at high speed and they do not come on.

No i do not have a repair or service manual.

Regards

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