Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[amba]

Last couple of days with hot weather have found that temp gauge starts to go beyond its usual mid point(95)and today coming home in slow traffic almost reached 100....this did come down when traffic got moving again but this must just then be due to air flowing quicker across rads.
When pulled onto drive had both front fans running,but unsure if slow or fast ?? and main radiator fan also running...these stopped together after about 3 mins from turning off ignition.Have no coolant loss/water pump replaced approx 40k ago along with brand new radiator.Coolant flushed and replaced at start of year.
I intend to start with obvious and do a full flush of coolant and check for any debris in rad grille ...whist rad is out will also replace both fan sensors,but just want to fully understand fan sequence.

[bigdods]

This is for my Facelift, I think its the same for older ones although temps may be slightly different. IIRC its aircon on, one fan always runs at low speed. at 92deg th second fan kicks in at half speed. This is enough to bring the temp back down to ~88 then it cuts out. If the temp gets to 97 then the big fan comes on at mental speed and cools everythign down very quickly.

On mine the green fuse under the bonnet near the battery blew so low speed didnt work. Temp would climb to ~100 then this mental speed fan would come on. Blimey its loud.

If all the fans are running and its not cooling down then you could have a cooling system in need of some TLC.

But first check all those fuses by the battery !

[TestOmega]

Take with a grain of salt write-up about my car's operation (a wrong wheel drive version of the Omega, 2001 Cadillac Catera ).  Here goes and you have to abridge and possibly use own relay numbers,

Auxiliary Fans Low Speed: Electric Cooling Fan Low Speed Battery voltage is supplied to heater water auxiliary pump whenever ignition switch is on. When engine temperature reaches 212°F (100°C), primary cooling fan temperature switch stage 1 will close, enabling fan control relay K26 to energize. When fan control relay K26 energizes, battery voltage from fuse 52 is applied to auxiliary coolant fan 1 (auxiliary engine coolant fan 1 is wired in series with auxiliary engine fan 2, through normally closed contacts of fan control relay K52. This will cause auxiliary coolant fans 1 and 2 to operate at low speed. Fan control relay K26 will also supply battery voltage to engine coolant fan resistor, voltage passes through resistor to electric coolant fan. Engine coolant fan resistor will cause engine coolant fan to operate at low speed. Primary cooling fan temperature switch stage 1 contacts will open when coolant temperature reaches 203°F (95°C). This will turn all 3 fans off, unless air conditioning system is on.

Auxiliary Fans High Speed: When engine temperature reaches 221°F (105°C), secondary cooling fan temperature switch contacts will close and energize fan control relays K52 and K28. When fan control relay K52 energizes, it will ground terminal "B" of auxiliary engine coolant fan 1. Terminal "A" of auxiliary engine fan 1 still receives battery voltage from fan control relay K26. Auxiliary coolant fan 1 is no longer in series with auxiliary engine coolant fan 2 and will now operate at full speed. When fan control relay K28 is energized, battery voltage from fuse 40 will be applied to terminal "A" of auxiliary engine coolant fan 2. Auxiliary coolant fan 2 is no longer in series with auxiliary engine coolant fan 1 and operates at full speed. Terminal "B" of auxiliary coolant fan 2 is permanently grounded. With stage 1 contacts of primary cooling fan temperature switch closed, electric cooling fan will continue to operate. Secondary cooling fan temperature switch contacts will open when coolant temperature reaches 212°F (100°C). This will cause auxiliary engine coolant fans 1 and 2 to operate at low speed.

Electric Coolant Fan High Speed: When engine coolant temperature reaches 230°F (110°C), primary cooling fan temperature switch stage 2 will close energizing fan control relay K67. When fan control relay K67 energizes, battery voltage from fuse 42 will be applied directly to terminal "A" of engine coolant fan (bypassing engine coolant fan resistor ) and engine coolant fan will operate at full speed. All other operations that were taking place before coolant temperature reached 230°F (110°C) will remain in effect. Primary cooling fan temperature switch stage 2 contacts will open when coolant temperature reaches 221°F (105°C) and primary engine coolant fan will shut off. At coolant temperatures above approximately 230°F (110°C), all 3 coolant fans are operating at full speed. Only 5 of 6 relays operate at this time, unless air conditioning system is turned on. In this case, fan control relay K87 and A/C compressor relay K60 will also operate.

Engine Cooling Fans (A/C Operation): When A/C compressor is turned on, fan control relay K87 is energized and auxiliary engine coolant fans 1 and 2 will operate in low speed. In order to prevent inadmissible high refrigerant pressure in refrigerant circuit, auxiliary engine coolant fans 1 and 2 are switched from low speed to high speed at refrigerant pressures above approximately 275 psi. When pressure drops less than about 217 psi, auxiliary engine coolant fans 1 and 2 are switched back to low speed.

Water Auxiliary Pump: When ignition is off and engine coolant temperature reaches 212°F (100°C), primary cooling fan temperature switch stage 1 will close, enabling fan control relay K26 to energize. When fan control relay K26 energizes, battery voltage from fuse 52 is applied through normally closed auxiliary water pump relay K22, allowing water auxiliary pump to operate. Fan control relay K26 will also supply battery voltage to engine coolant resistor, allowing voltage to pass through resistor to electric cooling fan. Engine cooling fan resistor will cause engine cooling fan to operate at low speed. When engine coolant temperature reaches 203°F (95°C), primary cooling fan temperature switch stage 1 will open, de-energizing fan control relay K26. This will turn water auxiliary pump and engine cooling fan off.

The above is not my original write-up but an excerpt that I saved.

Regards.

[amba]

Thanks for advise,guys.
On checking further it looks to me like the 2 front fans on the aircon rad are running at slow speed with a/c on ,but even when temp got high they did not increase in speed,so are the 2 front fans twin speed ?
If so what relay or fuse controls the second speed?
Main water coolant fan does run ,but assume this is only a single speed system which operates via thermoswitch on top of rad by top hose?..what does the bottom thermoswitch control then ?

[bigdods]

so are the 2 front fans twin speed ?
If so what relay or fuse controls the second speed?

Without going out and playing (my car is parked miles away) IIRC one fan is low speed only, and will always be running as long as the aircon is not in eco mode. The other fan is dual speed - when things get too toasty it comes on a super speed and trust me you will know if this happens its loud !. Look in the tech guides may be a fuse layout in there. I am sure the fuses and relays are in the fusebox under the bonnet by the side of the battery. Just take each fuse out in turn to see if any are blown,

[amba]

I had a good read of the fuse /relay layout in the  guide provided bt Mark DTM and it seems that we have 3 relays involved in the cooling operation.
K87....Green....aux cooling fan
K67....Dark Blue....cooling fan relay
F52.....relay with aircon.
Can any body advise me which one will control the 2 speed operation of  the front fans,as I am now certain that both fans are only running at slow speed.

Guide makes no mention of any fuses only relays,so imagine it must be one of these that trips from single speed to fast,but can,t identify.

[Kevin Wood]

There's a complex arrangement of relays which control the fans. Sounds to me like it's either not getting hot enough to go to stage 2 or the thermo switch isn't switching. If a relay had failed something would happen IMHO.

I reckon it's not hot enough, TBH. Stage one happens at just under 100 deg.C but with the aircon on it doesn't change the fans.

Bear in mind that coolant with the correct antifreeze concentration and cooling system pressure won't boil until around 120 degrees C so you have some safety margin even if it gets to 100.

Kevin

[amba]

Yesterday and today,with air temp bit lower dash gauge has not gone beyond mid point from 95-100 so seems engine is getting enough air across it either with just air draft or from fans.I do remember that one of the cars fans used to sound like a jet engine taking off when temp used to de above mid 20,s so maybe the thermoswitches on rad are suspect .
I intend to take radiator out at some point and give it a good flush ready for winter so will replace both the switches then ..or maybee before if problem gets worse.
Are both switches identical ? and any one with access to part numbers would be helpfull.
Thanks

[Debs.]

Take with a grain of salt write-up about my car's operation (a wrong wheel drive version of the Omega, 2001 Cadillac Catera ).  Here goes and you have to abridge and possibly use own relay numbers,

Auxiliary Fans Low Speed: Electric Cooling Fan Low Speed Battery voltage is supplied to heater water auxiliary pump whenever ignition switch is on. When engine temperature reaches 212°F (100°C), primary cooling fan temperature switch stage 1 will close, enabling fan control relay K26 to energize. When fan control relay K26 energizes, battery voltage from fuse 52 is applied to auxiliary coolant fan 1 (auxiliary engine coolant fan 1 is wired in series with auxiliary engine fan 2, through normally closed contacts of fan control relay K52. This will cause auxiliary coolant fans 1 and 2 to operate at low speed. Fan control relay K26 will also supply battery voltage to engine coolant fan resistor, voltage passes through resistor to electric coolant fan. Engine coolant fan resistor will cause engine coolant fan to operate at low speed. Primary cooling fan temperature switch stage 1 contacts will open when coolant temperature reaches 203°F (95°C). This will turn all 3 fans off, unless air conditioning system is on.

Auxiliary Fans High Speed: When engine temperature reaches 221°F (105°C), secondary cooling fan temperature switch contacts will close and energize fan control relays K52 and K28. When fan control relay K52 energizes, it will ground terminal "B" of auxiliary engine coolant fan 1. Terminal "A" of auxiliary engine fan 1 still receives battery voltage from fan control relay K26. Auxiliary coolant fan 1 is no longer in series with auxiliary engine coolant fan 2 and will now operate at full speed. When fan control relay K28 is energized, battery voltage from fuse 40 will be applied to terminal "A" of auxiliary engine coolant fan 2. Auxiliary coolant fan 2 is no longer in series with auxiliary engine coolant fan 1 and operates at full speed. Terminal "B" of auxiliary coolant fan 2 is permanently grounded. With stage 1 contacts of primary cooling fan temperature switch closed, electric cooling fan will continue to operate. Secondary cooling fan temperature switch contacts will open when coolant temperature reaches 212°F (100°C). This will cause auxiliary engine coolant fans 1 and 2 to operate at low speed.

Electric Coolant Fan High Speed: When engine coolant temperature reaches 230°F (110°C), primary cooling fan temperature switch stage 2 will close energizing fan control relay K67. When fan control relay K67 energizes, battery voltage from fuse 42 will be applied directly to terminal "A" of engine coolant fan (bypassing engine coolant fan resistor ) and engine coolant fan will operate at full speed. All other operations that were taking place before coolant temperature reached 230°F (110°C) will remain in effect. Primary cooling fan temperature switch stage 2 contacts will open when coolant temperature reaches 221°F (105°C) and primary engine coolant fan will shut off. At coolant temperatures above approximately 230°F (110°C), all 3 coolant fans are operating at full speed. Only 5 of 6 relays operate at this time, unless air conditioning system is turned on. In this case, fan control relay K87 and A/C compressor relay K60 will also operate.

Engine Cooling Fans (A/C Operation): When A/C compressor is turned on, fan control relay K87 is energized and auxiliary engine coolant fans 1 and 2 will operate in low speed. In order to prevent inadmissible high refrigerant pressure in refrigerant circuit, auxiliary engine coolant fans 1 and 2 are switched from low speed to high speed at refrigerant pressures above approximately 275 psi. When pressure drops less than about 217 psi, auxiliary engine coolant fans 1 and 2 are switched back to low speed.

Water Auxiliary Pump: When ignition is off and engine coolant temperature reaches 212°F (100°C), primary cooling fan temperature switch stage 1 will close, enabling fan control relay K26 to energize. When fan control relay K26 energizes, battery voltage from fuse 52 is applied through normally closed auxiliary water pump relay K22, allowing water auxiliary pump to operate. Fan control relay K26 will also supply battery voltage to engine coolant resistor, allowing voltage to pass through resistor to electric cooling fan. Engine cooling fan resistor will cause engine cooling fan to operate at low speed. When engine coolant temperature reaches 203°F (95°C), primary cooling fan temperature switch stage 1 will open, de-energizing fan control relay K26. This will turn water auxiliary pump and engine cooling fan off.

The above is not my original write-up but an excerpt that I saved.

Regards.

 8-) IMHO: This informative post deserves to be in the Omega-information/maintenance-guides.

[Sir Tigger KC]

I've just replaced both fan switches, and still have the packets somewhere, I'll look for them tomorrow.

Just don't buy cheap pattern switches like I did when I put the new rad in 3 months ago...... 

[amba]

TiggerHayes...Thanks for help..I had intended using genuine parts so the numbers and idea of cost would be very helpfull...assuming they are the same from Facelift 2000 as yours is ,to my MiniFacelift 1998.

[Sir Tigger KC]

Seal ring x2 @ £1.45 each (24427589)  =   2.86
Switch x1 @ £32.72 (90458540)           = 32.72
Switch-temp x1 £25.16 (90376209)      = 25.16

Plus the VAT the total is £71.37    Not cheap I know, but its sorted my fan problems

I'm not sure if your car will have the same switches, but I'm sure the dealer will be able to find the right ones. 

Also I don't have one of those discount cards so if you have one it might be cheaper. Hope that helps

[amba]

Thanks for info..TiggerHayes.
They aren,t cheap are they ?but if they solve the problem well all good.
Just for info which one fits at the top and which at the bottom ?..but expect plug connections differ so may be obvious.

[Sir Tigger KC]

Sorry can't remember which is which, but as you say its obvious when you get going as the connectors are different 

As I said, all my fans are now working properly and I've even got aircon...... sort of