Coolant and A/C

[Itzhaky]

On my ’97 DeVille, when I turn the A/C on, the coolant gets too hot and I’m loosing water. Yesterday I had to stop the car (260 F) and I notice coolant leaking from a rubber tube that appears to be connected to the A/C compressor. Is there any operational connection between the A/C and the coolant system?

[Texas Jim]

There is a possibility that your FANS are not coming on. They should be on anytime the AC is on.

With the hood up and engine idling ... turn on AC and check to see if cooling fans are coming on. If not, check fuses, wiring etc.

[Ranger]

No connection. Cooling and A/C are two separate systems. If there is coolant dripping off of an A/C line, it is coming from somewhere else.

[secretagentman]

On my ’97 DeVille, when I turn the A/C on, the coolant gets too hot and I’m loosing water. Yesterday I had to stop the car (260 F) and I notice coolant leaking from a rubber tube that appears to be connected to the A/C compressor. Is there any operational connection between the A/C and the coolant system?

I'm having a similar problem with my 99 Deville.... except I have confirmed the fans do operate when the A/C is on, however they do not run with the A/C off. Could this be a problem with the PCM?? and if so where is the PCM located on this vehicle? I have a electrical schematic that shows the PCM to control the relays that supply voltage to the cooling fans...

IN A NUTSHELL: Fans operate with A/C ON which leads me to believe the relays are good. A/C off fans do not come on and car overheats. HELP!

[BodybyFisher]

On my ’97 DeVille, when I turn the A/C on, the coolant gets too hot and I’m loosing water. Yesterday I had to stop the car (260 F) and I notice coolant leaking from a rubber tube that appears to be connected to the A/C compressor. Is there any operational connection between the A/C and the coolant system?

I'm having a similar problem with my 99 Deville.... except I have confirmed the fans do operate when the A/C is on, however they do not run with the A/C off. Could this be a problem with the PCM?? and if so where is the PCM located on this vehicle? I have a electrical schematic that shows the PCM to control the relays that supply voltage to the cooling fans...

IN A NUTSHELL: Fans operate with A/C ON which leads me to believe the relays are good. A/C off fans do not come on and car overheats. HELP!

The way the cooling fans operate is as follows:

1) with the AC ON, they come on immediately and run constantly, and you will not normally see wide ranges in temps

2) with the AC OFF, the come on when the coolant temp reaches 228 degrees and turn off when it reaches 217 (approximately, someone correct me if I have the on/off temps wrong, I have a mental block today). With the AC off you will see wider temp ranges on your coolant temp gage.

With the AC off, are your cooling fans coming on at about 226-228 degrees? Check your coolant concentration, if it is LESS than 50/50 you might be boiling at too low of a temp causing your overheating.

Have you checked for codes? If your fans are not coming on you MIGHT have a problem with your coolant temp sensor. Check your codes.

[BodybyFisher]

On my ’97 DeVille, when I turn the A/C on, the coolant gets too hot and I’m loosing water. Yesterday I had to stop the car (260 F) and I notice coolant leaking from a rubber tube that appears to be connected to the A/C compressor. Is there any operational connection between the A/C and the coolant system?

Specifically tell us where the coolant was found, it sounds like you might have confused that rubber tube with the overflow tube that is connected to the tank.

If you are leaking coolant you need to find out where it it coming from, check the following

Check your radiator/tank cap to see if its dirty or bad, if it has not been replaced, replace it, if it is blowing off too soon, you will see coolant coming out of a rubber tube that hangs down toward the street,

Check your tank for cracks,

Check the heater hoses under the tank, there are three,

Check the purge line to be sure its not leaking,

Consider having a radiator shop do a cooling system pressure test to find the leak.

[secretagentman]

The way the cooling fans operate is as follows:

1) with the AC ON, they come on immediately and run constantly, and you will not normally see wide ranges in temps

2) with the AC OFF, the come on when the coolant temp reaches 228 degrees and turn off when it reaches 217 (approximately, someone correct me if I have the on/off temps wrong, I have a mental block today). With the AC off you will see wider temp ranges on your coolant temp gage.

With the AC off, are your cooling fans coming on at about 226-228 degrees? Check your coolant concentration, if it is LESS than 50/50 you might be boiling at too low of a temp causing your overheating.

Have you checked for codes? If your fans are not coming on you MIGHT have a problem with your coolant temp sensor. Check your codes.

Thank you for your response.

With the AC off, are your cooling fans coming on at about 226-228 degrees? NO

I know for sure the mixture is NOT 50/50 at this point. The other day I replaced the temp sensor (located below the EGR pipe- please correct me if I am wrong) and put new coolant in. I ran the car to purge the system w/ A/C OFF. The fans never came on and the coolant boiled out. The car temp went up to like 240 + degrees, but NO fans. (???)

[BodybyFisher]

OK if they are NOT coming on you have a problem check your relays, or fuses. I believe the cooling fans use the same fuse as the AC COMP.

check the computer codes a bad coolant temp sensor could be giving a BAD temp to the PCM

If the coolant is not 50% coolant, you will boil at a lower temp

CHECK FOR CODES asap

[fivepointohman]

OK if they are NOT coming on you have a problem check your relays, or fuses. I believe the cooling fans use the same fuse as the AC COMP.

check the computer codes a bad coolant temp sensor could be giving a BAD temp to the PCM

If the coolant is not 50% coolant, you will boil at a lower temp

CHECK FOR CODES asap

When the A/C is turned on the cooling fans will come on to cool the refrigerant from the A/C. If the fans do not turn on that is your issue right there... There is a relay and a large fuse as well as the small 20/30Amp fuses located un the hood.

The dripping you see is it colored or just water, cause if its just water, that is normal from the cold refigerant lines creating condesation from the air around them... not to worrry. If it's coolant it's from overheating...

[secretagentman]

OK if they are NOT coming on you have a problem check your relays, or fuses. I believe the cooling fans use the same fuse as the AC COMP.

check the computer codes a bad coolant temp sensor could be giving a BAD temp to the PCM

If the coolant is not 50% coolant, you will boil at a lower temp

CHECK FOR CODES asap

When the A/C is turned on the cooling fans will come on to cool the refrigerant from the A/C. If the fans do not turn on that is your issue right there... There is a relay and a large fuse as well as the small 20/30Amp fuses located un the hood.

The dripping you see is it colored or just water, cause if its just water, that is normal from the cold refigerant lines creating condesation from the air around them... not to worrry. If it's coolant it's from overheating...

1st, thank you all for your responses once again.... I'm a Honda tech so I'm a little lost.

Fans operate normal with A/C on - car does not overheat... With A/C off fans DO NOT ever turn on and the car will overheat if allowed to run. Now, FANs work with A/C on Which leads me to believe that the relays and fuses are good (but I could be wrong.) According to the electrical diagram, the fan relays are controlled by the PCM. Has anyone ever seen the PCM (specifically the relay control portion) fail in this way? The PCM seems like it is not reacting to the temp sensor values. It should send current to the relays to have the fans come on. I have seen a range of 190s to about 240 degrees before I shut it down. Anyways, I hope this thread makes sense..

[Ranger]

I'd check the ECT switch. Maybe it is not sending the info to the PCM.

[BodybyFisher]

With the AC off, are your cooling fans coming on at about 226-228 degrees? NO

I know for sure the mixture is NOT 50/50 at this point. The other day I replaced the temp sensor (located below the EGR pipe- please correct me if I am wrong) and put new coolant in. I ran the car to purge the system w/ A/C OFF. The fans never came on and the coolant boiled out. The car temp went up to like 240 + degrees, but NO fans. (???)

************************************************************

Don't parts replace, if you checked the codes, and your temp sensor was bad, the PCM would have stored a code to that fact. You replaced the coolant temp sensor for no reason. Before you go ANY further, if you have not done so check the codes. THEN, check the coolant fan fuse/breaker, to be sure its NOT bad or corroded.

If you don't know how to check your codes go to the HOW TO at the top of this page see DTC codes and follow the directions if you find any codes post them here

[BodybyFisher]

OK if they are NOT coming on you have a problem check your relays, or fuses. I believe the cooling fans use the same fuse as the AC COMP.

check the computer codes a bad coolant temp sensor could be giving a BAD temp to the PCM

If the coolant is not 50% coolant, you will boil at a lower temp

CHECK FOR CODES asap

When the A/C is turned on the cooling fans will come on to cool the refrigerant from the A/C. If the fans do not turn on that is your issue right there... There is a relay and a large fuse as well as the small 20/30Amp fuses located un the hood.

The dripping you see is it colored or just water, cause if its just water, that is normal from the cold refigerant lines creating condesation from the air around them... not to worrry. If it's coolant it's from overheating...

1st, thank you all for your responses once again.... I'm a Honda tech so I'm a little lost.

Fans operate normal with A/C on - car does not overheat... With A/C off fans DO NOT ever turn on and the car will overheat if allowed to run. Now, FANs work with A/C on Which leads me to believe that the relays and fuses are good (but I could be wrong.) According to the electrical diagram, the fan relays are controlled by the PCM. Has anyone ever seen the PCM (specifically the relay control portion) fail in this way? The PCM seems like it is not reacting to the temp sensor values. It should send current to the relays to have the fans come on. I have seen a range of 190s to about 240 degrees before I shut it down. Anyways, I hope this thread makes sense..

This is interesting, the fans work with the AC on just fine

But with the AC off, they are never triggered on. This is covered in the service manual in a diagnotic tree, let me take a look and see what I find. I will get back to this thread. Definately check your codes, as Ranger noted a Coolant Temp Sensor would cause this, but you replaced it? Ill look at the diagnotic tree asap.

[WarrenJ]

With the A/C off you should be able to drive the car all day long without the fans ever being commanded "ON" (as long as the ambient temperature is below 80F or so).

It sounds as though you might have a restriction in the coolant loop. I'd be looking at the thermostat. But that's just me.

Regards,

Warren

EDIT: In post #5 of this thread <a href="http://caddyinfo.ipbhost.com/index.php?showtopic=17555" target="_blank">http://caddyinfo.ipbhost.com/index.php?showtopic=17555</a> is my attachment of the fan operation in a '98 Eldorado. You might find it a handy reference even though it is not for your year/model car.

[WarrenJ]

Here is the actual wiring diagram for your cooling fans.

Regards,

Warren

1997DevilleFans.pdf

[BodybyFisher]

As you can see, Warren posted some valuable diagnosis information, look that over.

This is a description out of my manual of:

Low Speed Conditions

The PCM turns on the cooling fans at low speed when the engine coolant temperature exceeds 106 degrees C (222 degrees F). The cooling fans turn off when the engine coolant temp falls below 102 degrees C (215 degrees F). The PCM monitors engine coolant temp using the engine coolant temperature sensor input on YEL (410).

The PCM also activates low speed conditions it the transaxle exceeds 115 degrees C. The cooling fans turn off when the transaxle temp falls below 110 degrees C.

The Heater and AC Programmer requests the PCM to turn on the cooling fans at low speed through the Class II data line when the AC high side refrigerant temp exceeds 50 degrees C. The programmer requests that the cooling fans turn off once the AC high side refrigerant temp falls below 47 degrees C.

The PCM turns on the cooling fans at low speed if a low coolant level is detected and the engine coolant exceeds 80 degrees C and turns off when engine coolant drops to 76 degrees C.

Low Speed Operation

Low speed cooling fan operation occurs when the PCM grounds the Cooling Fan 1 Relay coil on CKT 335. With only Cooling Fan Relay energized, voltage is applied to both the LH and RH cooling fan motors. Power is supplied to the motors through the Cooling Fan 1 Relay contact circuits, BLK (532), WHT (504) and LT BLU (409), and the Cooling Fan 2 Relay contacts. The two motos are connected through a series circuit. The circuit divides the voltage applied by COOL, FNS Maxi Fuse between the two motors. The division of the voltage causes the motors to operate at a lower speed. In series mode, the fans are grounded through BLK (350) and ground G107.

Hope this helps, Mike

[WarrenJ]

Itzhaky,

Please don't forget to let us know the endgame. After all, that is how this community learns.

Regards,

Warren

[BodybyFisher]

Itzhaky and secretagentman,

Please check your DTC codes before you go any further, that is important, as we are flying blind here. Mike

[Dudge]

Did you ever get this resolved? I'm having the exact same problem with my brothers '00 STS. It's driving me crazy! I replaced the coolant temp sensor about an hour ago and it didn't solve the problem. I checked the codes (thanks to this site) and the only current code I was getting was P0420 (Which is the converter). The passenger side fan comes on when the A/C is turned on, but if it's not then it gets hot and boils out the top of the purge tank. We replaced the 3 relays in the fuse block under the hood. Are there any other fuses or relays I can check? Thanks for the help.

[JimD]

Did you ever get this resolved? I'm having the exact same problem with my brothers '00 STS. It's driving me crazy! I replaced the coolant temp sensor about an hour ago and it didn't solve the problem. I checked the codes (thanks to this site) and the only current code I was getting was P0420 (Which is the converter). The passenger side fan comes on when the A/C is turned on, but if it's not then it gets hot and boils out the top of the purge tank. We replaced the 3 relays in the fuse block under the hood. Are there any other fuses or relays I can check? Thanks for the help.

A 2000 Seville fan control system is almost certain to be different than a 1997 Deville system. You might get better information by starting a new post.

But from my 1998 Seville Service Manual (1998 - 2004 Sevilles are closer than sisters) in addition to the 3 relays you found, there are two fuses under the hood; both 30A and labeled COOL FAN 1 and COOL FAN 2.

Here is how the fans operate for a 1998 Seville. With A/C ON, both fans operate continuously.

With A/C OFF, both fans are commanded ON at low speed (they are connected in series) when the coolant temperature reaches ~~ 223 degrees F.

From your description, my 1st guess would be the LH (Fan 1) fan motor has failed, or the wiring is corroded/damaged, which would prevent both fans from operating (in series) when the coolant temperature reaches ~~ 223 degrees F.