I just had my blend motors on my NAS spec 2000 P38 replaced by a reputable shop. I have two concerns.

The first is hopefully and easy fix. The front, far left vent will not open. The louvers all work fine. It is the door that is open and closed by the dial. Can I just pull the vent cover off and open the door? What might be causing this?

The second relates to the force of the air coming from the upper center dash vents. It feels a bit anemic especially compared to the footwell vents. It's been so long since I had upper vents that worked on this Rover that I've forgotten how it should feel. How strongly should the air be blowing out from those upper vents? I know that's a vague question but currently it just feels week.

Thanks,

It depends on the position of the distribution motor flaps. If it is blowing out of the footwell vents then there will be less coming out of the face vents. If it is set so that it is only coming out of the face vents, with the blowers on full, it should give you a good blast. The HEVAC automatically adjusts the distribution flaps depending on where it thinks the air is needed most to get the interior temperature at what you have set it for.

If only one blower is working, most of the airflow will be blown out the side where it isn't working. Easy enough to check by taking the pollen filters out and having a look down the hole.

Also, to add to the above, check that none of your duct work has become disconnected, or the seals on the duct work disintegrated. I improved mine by spending a couple of hours under the dash with a roll of duct tape sealing up vent joints and found one joint that had come apart.

thanks for all the info.

looking at the P38 Workshop Manual I'm seeing two blower motors. One on the right and one on the left.

The Manual doesn't clearly state which blower motor does what, unless of course, I just overlooked it. If anyone knows the page number that does spell out what each one does off the top of their head, feel free to share it.

My assumption is that the right hand blower handles air on the right hand side and the left hand blower handles air on the left side of the cabin. Is this correct?

Or does one blower handle the footwells and the other handle the face level vents and windscreen vents?

First guess was correct, left and right. However, the ducts from each come to the heater matrix and then split again after it. If only one blower is working the airflow from the working one gets to the heater matrix and has a choice of which way to go, through the matrix or across to the other side and out where the air would normally come in. That will result in not a lot of air out of the vents.

Gilbertd wrote:

First guess was correct, left and right. However, the ducts from each come to the heater matrix and then split again after it. If only one blower is working the airflow from the working one gets to the heater matrix and has a choice of which way to go, through the matrix or across to the other side and out where the air would normally come in. That will result in not a lot of air out of the vents.

Thanks, Richard.

I am getting much weaker air from the face vents and the windscreen vents even when only the face vents or the defrost is selected. The foot well blows at full force.

This leads me to believe the shop that replaced the blend motors did not reconnect the duct work properly.

Either that or the linkage on the distribution motor wasn't fitted properly. They shouldn't have needed to touch it but the distribution motor drives 3 sets of gears that operate different flaps and if not all are moving that will cause the same problem. First thing to check is that both blowers are working. Easy enough by taking the pollen filters out and looking down the hole.

Techs at the shop are saying that the left side motor is not working. They think there is a short somewhere because they can manually turn on the blower motor. Assuming they are correct, does this point to a HVAC control unit?

Attached to the blower is a controller, the HEVAC tells the controller what speed it wants the blower to run at and that powers it. So if they mean they can put power straight onto the motor and it works, it's the controller. It fails in one of two ways, either the blower does nothing or it runs at maximum speed all the time. Blower needs to come out to change it but as it was made by Valeo, it is the same as that used on various French cars. One of these https://www.ebay.co.uk/itm/164324521085 is what you need.

check the relays on the fuse board , just replace them and inspect the board for burning and cracking. if this is all good then it could be the fan that is sus or both.

shop called yesterday and said they found a burnt relay in engine bay fuse panel. replaced it and all is working as it should be.

i'm hoping it was just age that caused the burnt relay.

as long as you don't burn another relay then you need to look at the fan
PS remove the relays and look at the fuse board as well

Those two relays (6 and 7) carry a fair amount of current, up to 15A when the blowers are running, so it's worth replacing them with higher current rated ones. The originals are rated at 30A but I've swapped mine for 40A ones. The state of the contacts in the fusebox is also important as even a tiny amount of resistance in there will cause them to get hot.

all seems to be working as it should.

I'll update this thread later if needed.

Thanks to everyone who pointed me in the right directions.