Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: MonzaGSE on 29 December 2022, 15:45:12

Title: 1994 Omega x20xev cooling fan constantly on full
Post by: MonzaGSE on 29 December 2022, 15:45:12
Girlfriend came home now complaining that her Omega made a strange noise. Quickly found the engine cooling fan running flat out. Outside temp 0C  Engine temp on the dash showed completely normal. Coolant level normal. On disconecting temp sensor on radiator the fan stops. Relay in enginebay relay box clicks when temp sensor gets reconnected. Fan starts up and runs on full as soon as tempsensor is reconnected. Upper radiator hose varm and lower hose cold. Nice warmth in cabin heater. Radiator probably 3 months old.
Are the sensor itself the most likely culprit?
Title: Re: 1994 Omega x20xev cooling fan constantly on full
Post by: Doctor Gollum on 29 December 2022, 15:48:57
Sounds like it, or the relay. Swapping the relay for another fan one will test and confirm either way.  ;)
Title: Re: 1994 Omega x20xev cooling fan constantly on full
Post by: TheBoy on 29 December 2022, 20:22:31
Sounds like sensor :y

There are different types that look the same, so go by the ident code stamped on it.
Title: Re: 1994 Omega x20xev cooling fan constantly on full
Post by: MonzaGSE on 10 January 2023, 12:29:12
Update: Tried swapping the relay but made no difference. So ordered a new sensor. Car has been in use daily since problem occured. Cooling fan has been running full blast after maybe 10 min driving.  New sensor arrived yesterday so changed it today. Car ran fine all the way to work today with no cooling fan coming on.
So hopefully the problem is now fixed:)
Title: Re: 1994 Omega x20xev cooling fan constantly on full
Post by: TheBoy on 10 January 2023, 12:50:07
Every time I've seen a failed sensor on an Omega, its resulted in the fan on full.
Title: Re: 1994 Omega x20xev cooling fan constantly on full
Post by: Doctor Gollum on 10 January 2023, 18:01:14
Depends which sensor/switch has failed ;)
Title: Re: 1994 Omega x20xev cooling fan constantly on full
Post by: TheBoy on 10 January 2023, 18:07:40
Depends which sensor/switch has failed ;)
There is either 1 or 2, depending on engine spec.  Most are 1.

IME, failure mode on them tends to be short, bring fan on full chat
Title: Re: 1994 Omega x20xev cooling fan constantly on full
Post by: BazaJT on 10 January 2023, 18:47:53
Mine has two radiator switches and 3 fans and all 3 when they kick in don't stop,so if it's one of the radiator switches how do I know which one? Also as neither switch is original how do I know it's got the correct ones fitted or if I'm buying the correct replacement?
Title: Re: 1994 Omega x20xev cooling fan constantly on full
Post by: Doctor Gollum on 10 January 2023, 19:39:53
There's a guide in the Maintenance section ;)

Basically uplug the sensor and bridge the appropriate terminals  ;)
Title: Re: 1994 Omega x20xev cooling fan constantly on full
Post by: VXL V6 on 10 January 2023, 21:46:40
Had similar on one of the old DTi's. Smacking one of the Orange under bonnet relays resolved the issue until a new one was fitted. Be worth a check but if relay is clicking it sounds more like a sensor.
Title: Re: 1994 Omega x20xev cooling fan constantly on full
Post by: Doctor Gollum on 10 January 2023, 21:52:58
There's a guide in the Maintenance section ;)

Basically uplug the sensor and bridge the appropriate terminals  ;)
Having said that, carefully unplugging the switches in turn with the ignition on/engine off should easily pinpoint which one is the culprit ;)