P38 Air/Con Motors

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Radar1946

Radar1946

Active Member
Posts
362
Location
Lichfield, Staffordshire
I have arranged for an a/c service at home on Wednesday 1st . I decided to check as much as I can before he arrives. Checked all fuses and relays, RL-6 relay was missing so I put one in and as soon as I switch to the first click on the key, the motors start blowing. I plugged in my diagnostic tool and found only 2 faults.
First one is +12volt/other circuit permanent and second one is Right blend door motor circuit fault..
Anyone with ideas?
 
Hi I have the same problem bought new motors for all 3 blend motors a about 4 years ago and still haven’t fitted them yet. I am put off by the fact you have to strip the dash to fit them
Let me know how you get on with the aircon service
Yours Terry
 
Radar1946 said:
I have arranged for an a/c service at home on Wednesday 1st . I decided to check as much as I can before he arrives. Checked all fuses and relays, RL-6 relay was missing so I put one in and as soon as I switch to the first click on the key, the motors start blowing. I plugged in my diagnostic tool and found only 2 faults.
First one is +12volt/other circuit permanent and second one is Right blend door motor circuit fault..
Anyone with ideas?
Click to expand...

RL 6 is not involved with the aircon fans, relays 13, 14, 18 & 19 plus X315 dual pressure switch. Could be the fuse box is toast or the dual pressure switch. I'm not aware that any problems with the aicon other than from the HEVAC will show on diagnostics.
 
oldtel said:
Hi I have the same problem bought new motors for all 3 blend motors a about 4 years ago and still haven’t fitted them yet. I am put off by the fact you have to strip the dash to fit them
Let me know how you get on with the aircon service
Yours Terry
Click to expand...
You don't have to strip the dash to fit blend motors and blend motors are not the same as aircon fans
 
Hi I am sorry I must have been mistaken I thought radar1946 said he had a fault the left blend motor was shot sorry I shall keep quiet and let the people that know deal with the problem
Yours Terry
 
It's not the air con fans that come on it is the blower motors in the car.
I started the engine and the fans slowed down and I could adjust the speed on the speed knob on the dash.
I will certainly let you know how I get on with the service.
 
Radar1946 said:
It's not the air con fans that come on it is the blower motors in the car.
I started the engine and the fans slowed down and I could adjust the speed on the speed knob on the dash.
I will certainly let you know how I get on with the service.
Click to expand...
In that case, check for signs and smells of burning in the fuse box. On one of my cars the blower motors cannot be turned off completely, depends on the version of the HEVAC.
 
Datatek said:
No, don't keep quiet, all contributions are welcome even when they are off the mark:D
Click to expand...

Well here goes then!;)
Typically rangeroverish, when a blower fan fails it goes full belt. I think it is sort of 'on all the time and is reduced by a controlling voltage'. (Is that right O Wise Ones?) Fortunately, and quite rightly, there is a separate fuse for each (ie driver's side and passenger's side).
The driver's side blower has failed in this way (on my 2001 DT) and so I've removed the fuse. The passenger side one still works, is controllable, and does the biz, but is not as powerful as the driver's side and so winter de-misting is a little slower...
Its not the work that's putting me off but the cost of a new blower - hunnerds! :eek:
Perhaps I'm missing the point here (not unheard of!:oops:) but I think these blowers are for air distribution, heated or cooled, and
as such ​
are not part of the aircon.

I'm also checking my aircon and trying to put it back together. Does anyone (SaintV8?) have a schematic showing any NRVs etc? That would be really useful
 
Had both fans out on my 2000 M/y p38 to clean and oil them if I remember right the drivers side you have to twist a bit of cable duct out the way to get it out but it wasnt that difficult to remove and replace.
 
plumbfisher said:
Well here goes then!;)
Typically rangeroverish, when a blower fan fails it goes full belt. I think it is sort of 'on all the time and is reduced by a controlling voltage'. (Is that right O Wise Ones?) Fortunately, and quite rightly, there is a separate fuse for each (ie driver's side and passenger's side).
The driver's side blower has failed in this way (on my 2001 DT) and so I've removed the fuse. The passenger side one still works, is controllable, and does the biz, but is not as powerful as the driver's side and so winter de-misting is a little slower...
Its not the work that's putting me off but the cost of a new blower - hunnerds! :eek:
Perhaps I'm missing the point here (not unheard of!:oops:) but I think these blowers are for air distribution, heated or cooled, and
as such ​
are not part of the aircon.

I'm also checking my aircon and trying to put it back together. Does anyone (SaintV8?) have a schematic showing any NRVs etc? That would be really useful
Click to expand...
If the fan is going full belt as you put it, the fan has not failed, it's the speed controller that has failed and they can be repaired. From memory I think the transistor used for speed control is a 2N3055, they can be purchased for pennies. The hard bit is getting the blower motor out.
 
As ever, thanks for your deeper knowledge of these things! Is this in Rave? Or is the transistor in the blower motor?
Q2 - Is there a NRV in the aircon system? Someone once told me there was but I can't see why there would be...
 
plumbfisher said:
As ever, thanks for your deeper knowledge of these things! Is this in Rave? Or is the transistor in the blower motor?
Q2 - Is there a NRV in the aircon system? Someone once told me there was but I can't see why there would be...
Click to expand...
The speed regulator assembly is I believe attached to the blower motor. I have never had to take one out so not sure precisely where it is on the blower motor, maybe on the housing, I just know how it works:)
 
The speed regulators are indeed attached to the blower motors. They respond to signals received from the Hevac unit. However there is a temp sensor on one of the steel pipes going to the matrix. This feeds the Hevac unit with coolant temp info. In heating mode the fans even if set to full speed, should not go to full speed until the coolant reaches a certain temperature. As the temp rises so will the fan speed for demist or heating etc.
 
wammers said:
The speed regulators are indeed attached to the blower motors. They respond to signals received from the Hevac unit. However there is a temp sensor on one of the steel pipes going to the matrix. This feeds the Hevac unit with coolant temp info. In heating mode the fans even if set to full speed, should not go to full speed until the coolant reaches a certain temperature. As the temp rises so will the fan speed for demist or heating etc.
Click to expand...
One fan is working normally he say's so I can't see that being the problem but you never know.
 
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