So where is the AC relay?

judgeman · Sep 16th, 2003, 20:50

Following on from the 'HELP! My T5 battery keeps dying!' thread, I have taken members advice and removed any hint of car phone wiring. Though I noticed when removing the power leads from the battery that the in line fuse in the positive cable was blown, so it can't have been making a circuit. Hmm.

The car went into the auto electricians yesterday, where they changed the battery to a 75ah unit - a bit better than the feeble 55ah supplied from the motor spares place!

The car stayed in overnight, but the electrician could find no drain on the battery. He rekons the alternator is charging fine, and can see nothing wrong with the voltage regulator on the alternator.

However, speaking to the garage, we think it might be a sticking air conditioning relay (the garage say they had a similar problem once before). Simple, remove the relay and see if that is the problem. Er, no. Neither the garage, or the auto electrician (with his fix all book of auto circuits and electrics) can find where the relay is!

Can anyone help???

Has anyone else had a similar problem?

I would be grateful for any help anyone can give me - I know I now have a bigger battery, but I'm not convinced this will cure all.

sholtby · Sep 16th, 2003, 21:14

Does the alternator stay hot long after the engine is switched off? If so the diodes in the alternator have failed and the battery will 'back feed' through it causing the heat. With the engine running the alternator will appear to be OK giving 14 volts.
Youll have to check as I recommended this to a guy with a Renault and his alternator didnt use diodes but a seperate relay instead. Most alternators use diodes in which case youll need a rebuild or replacement.

Simon

Chris_Rogers · Sep 16th, 2003, 21:27

Relay is behind the glove box, it may be simpler just to remove the fuse.

judgeman · Sep 16th, 2003, 21:38

Thanks guys, diodes sounds like it to me, but need to check if it gets hot as sholtby suggests. Seems to me anyway that it would just be easier to replace the alternator and voltage regulator altogether.

Getting to the relay behind the glovebox shouldn't prove to difficult - I had the glove box out at the weekend to remove all traces of the car phone wiring.

I suggested removing the fuse to the auto electrician - but as he pointed out this also diables the heater fan. (though this could be the next step if likely to leave the car in the drive for a few days to check).

judgeman · Sep 16th, 2003, 21:39

Nearly forgot - if I go for the relay behind the glove box, how do I identify it?

Rooster · Sep 16th, 2003, 22:18

If my memory serves me correct there is 2 relays under the glovebox and they are both green, think they are both for the aircon but not 100% sure.

judgeman · Sep 17th, 2003, 18:23

Okay, so anyone out there wanna hire a guy to remove their glovebox? Piece of cake! And there they were! Two green relays!

I removed them both (careful to mark up which was left and right!), and putting my multi meter (bought one at the weekend, have been meaning to for years - You just gotta have one of these if doing anything remotely related to electrics on your car) accross the relay contacts - one appears to be sticking open!

Though I'm not an electrician, it was 5:30pm and the auto electricians were closed. So will check with the Oracle (my dad, a whizz with anything sparky) this weekend - a good run of 300 miles from Skipton, North Yorks, to Fareham, Hampshire!

A note about removing these relays - it appears that they are on the same circuit as the fan (they certainly use the same fuse), so I'll be leaving the relays out overnight, and replacing them for the drive tomorrow. A fan is definitely essential even of air con is not!

Watch this space...

pettaw · Sep 22nd, 2003, 13:08

Can you not just use your multi-meter as an ammeter to check current drain? Should be only a few milliamps.

Just a thought

Andy

judgeman · Sep 22nd, 2003, 19:19

Thanks mate, will try that.

Incidentally, tested the relays at the weekend, but both performing okay.

Spoke to a VOC member at the weekend with an 850, who had a similar problem with flat batteries. Turns out the Volvo ones were useless, and died within three months (unlike my 3 days!!!). So he fitted a Bosch battery and despite being in the car a year when the car was serviced without any problems, Volvo said that battery needed replacing as their testing gadget said it was dead. That was 9 months ago, and it hasn't let him down yet.

I also had a look at rewiring the knackered towing electrics. Too complicated for me because of the bulb integrity system. That'll be one for the autoelectrician! However, whilst checking where the previous owner has scotchlocked the current wires to the corresponding wiring loom wires (and earth to the electric arial earth???!!!), I picked up the bulb integrity 'box' looked at it, decided not to mess with the towing electrics, put it back and thought nothing of it. Next time I started the car I noticed the bulb failure warning light in the dashboard (only on during start up...!) So have I unwittingly sorted another problem out???!!!

Sep 16th, 2003, 20:50	#1
judgeman Senior Member Last Online: Apr 5th, 2024 17:46 Join Date: Dec 2002 Location: Skipton	So where is the AC relay? Following on from the 'HELP! My T5 battery keeps dying!' thread, I have taken members advice and removed any hint of car phone wiring. Though I noticed when removing the power leads from the battery that the in line fuse in the positive cable was blown, so it can't have been making a circuit. Hmm. The car went into the auto electricians yesterday, where they changed the battery to a 75ah unit - a bit better than the feeble 55ah supplied from the motor spares place! The car stayed in overnight, but the electrician could find no drain on the battery. He rekons the alternator is charging fine, and can see nothing wrong with the voltage regulator on the alternator. However, speaking to the garage, we think it might be a sticking air conditioning relay (the garage say they had a similar problem once before). Simple, remove the relay and see if that is the problem. Er, no. Neither the garage, or the auto electrician (with his fix all book of auto circuits and electrics) can find where the relay is! Can anyone help??? Has anyone else had a similar problem? I would be grateful for any help anyone can give me - I know I now have a bigger battery, but I'm not convinced this will cure all.

Sep 16th, 2003, 21:14	#2
sholtby Premier Member Last Online: May 26th, 2010 20:17 Join Date: Dec 2002 Location: north east	RE: So where is the AC relay? Does the alternator stay hot long after the engine is switched off? If so the diodes in the alternator have failed and the battery will 'back feed' through it causing the heat. With the engine running the alternator will appear to be OK giving 14 volts. Youll have to check as I recommended this to a guy with a Renault and his alternator didnt use diodes but a seperate relay instead. Most alternators use diodes in which case youll need a rebuild or replacement. Simon

Sep 16th, 2003, 21:27	#3
Chris_Rogers VOC Member Last Online: Apr 10th, 2017 16:55 Join Date: Jan 1970 Location: South Kent Coast	RE: So where is the AC relay? Relay is behind the glove box, it may be simpler just to remove the fuse.

Sep 16th, 2003, 21:38	#4
judgeman Senior Member Last Online: Apr 5th, 2024 17:46 Join Date: Dec 2002 Location: Skipton	RE: So where is the AC relay? Thanks guys, diodes sounds like it to me, but need to check if it gets hot as sholtby suggests. Seems to me anyway that it would just be easier to replace the alternator and voltage regulator altogether. Getting to the relay behind the glovebox shouldn't prove to difficult - I had the glove box out at the weekend to remove all traces of the car phone wiring. I suggested removing the fuse to the auto electrician - but as he pointed out this also diables the heater fan. (though this could be the next step if likely to leave the car in the drive for a few days to check).

Sep 16th, 2003, 21:39	#5
judgeman Senior Member Last Online: Apr 5th, 2024 17:46 Join Date: Dec 2002 Location: Skipton	RE: So where is the AC relay? Nearly forgot - if I go for the relay behind the glove box, how do I identify it?

Sep 16th, 2003, 22:18	#6
Rooster Speed freak Last Online: Apr 3rd, 2020 22:04 Join Date: Nov 2003 Location: Yorkshire	RE: So where is the AC relay? If my memory serves me correct there is 2 relays under the glovebox and they are both green, think they are both for the aircon but not 100% sure. __________________ 04 XC90 D5 --- Big bus 00 pug 306HDi --- Run about 88 pug 309GTi --- Project track car 07 CB600 Hornet --- 2 wheel fun

Sep 17th, 2003, 18:23	#7
judgeman Senior Member Last Online: Apr 5th, 2024 17:46 Join Date: Dec 2002 Location: Skipton	RE: So where is the AC relay? Okay, so anyone out there wanna hire a guy to remove their glovebox? Piece of cake! And there they were! Two green relays! I removed them both (careful to mark up which was left and right!), and putting my multi meter (bought one at the weekend, have been meaning to for years - You just gotta have one of these if doing anything remotely related to electrics on your car) accross the relay contacts - one appears to be sticking open! Though I'm not an electrician, it was 5:30pm and the auto electricians were closed. So will check with the Oracle (my dad, a whizz with anything sparky) this weekend - a good run of 300 miles from Skipton, North Yorks, to Fareham, Hampshire! A note about removing these relays - it appears that they are on the same circuit as the fan (they certainly use the same fuse), so I'll be leaving the relays out overnight, and replacing them for the drive tomorrow. A fan is definitely essential even of air con is not! Watch this space...

Sep 22nd, 2003, 13:08	#8
pettaw Forum Support Team Last Online: Jul 23rd, 2023 15:29 Join Date: Jan 1970 Location: Glasgow, London	RE: So where is the AC relay? Can you not just use your multi-meter as an ammeter to check current drain? Should be only a few milliamps. Just a thought Andy

Sep 22nd, 2003, 19:19	#9
judgeman Senior Member Last Online: Apr 5th, 2024 17:46 Join Date: Dec 2002 Location: Skipton	RE: So where is the AC relay? Thanks mate, will try that. Incidentally, tested the relays at the weekend, but both performing okay. Spoke to a VOC member at the weekend with an 850, who had a similar problem with flat batteries. Turns out the Volvo ones were useless, and died within three months (unlike my 3 days!!!). So he fitted a Bosch battery and despite being in the car a year when the car was serviced without any problems, Volvo said that battery needed replacing as their testing gadget said it was dead. That was 9 months ago, and it hasn't let him down yet. I also had a look at rewiring the knackered towing electrics. Too complicated for me because of the bulb integrity system. That'll be one for the autoelectrician! However, whilst checking where the previous owner has scotchlocked the current wires to the corresponding wiring loom wires (and earth to the electric arial earth???!!!), I picked up the bulb integrity 'box' looked at it, decided not to mess with the towing electrics, put it back and thought nothing of it. Next time I started the car I noticed the bulb failure warning light in the dashboard (only on during start up...!) So have I unwittingly sorted another problem out???!!!

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)