[spikemd]

2001 4.6 SE 92K miles

Well, looks like I am having an issue with my HVAC/blower motors/relays/fusebox? When it is really hot (100+) and I have the AC blowing hard, the dreaded hvac book fault comes on for me. I have done some basic troubleshooting and come up with a few ideas:

Pollen filters just replaced and clean. Blend motors work great with no issues. HVAC panel replaced by previous owner at 50k miles for pixels.

Both blower motors seem to be working and pushing good air and the air is still cold even when the book symbol comes on.
Fault only comes on when the AC is blowing at 2/3 to full blast and usually comes on when recirculating air.
I might hear a noise with the right blower motor after the book symbol comes on. (maybe something causing blower motor to run hard and causing relay to fail? still working on isolating this)

Checked RL7 relays for blower motors, ughh... brown noticed on yellow casing and fuse box shows shows small crack....checked other relays... also some showing brown at the edges indicating overheating...

So, I think I need a few things... a few more RL7 relays to replace any that appear cooked. Possibly fusebox, possibly blower motors...

I have also come across a post on another forum about a possible upgrade to the RL7 relay using a Hella 40A fuse from the Hella Safari light 5000 kit?? :? anyone do an upgrade to these blower motor relays? The posts states the relays run cooler, but I am always wary of putting in higher amp relays (40a vs 20a) as you could cook the wiring and/or blower motors.

I will try and replace the relays first, but at some point, I think a new fusebox will be needed. But of note, I have no other electrical problems with the vehicle and the fusebox has no signs of coolant contamination or dust in it. I also have the luxury of this being a California car with no rust or corrosion anywhere.

Thoughts on the upgrading the relay? best price for a fusebox? thanks.

 

[Rowant]

I also had hevac problems with the book symbol check out my post: viewtopic.php?f=3&t=39419
Do your relays and fuse box look anything like this? I eventually just went to an auto-electrical dealer and purchased a new relay. I took in my burnt one and they matched it up to a new one - different maker but rated the same and also a resistor relay like the factory item.
I found that buying the relay that way was a bloody site cheaper than the yellow Siemens item - nobody seems to know where to get that model over here. There are only two blower relays so any other suspect units will be for other circuits and have a look here to see what they might be for. Thanks to Viperover for use of picture and info. http://rangeroverworld.blogspot.com/201 ... chive.html

I have not replaced my fusebox as yet - the weather is lousy at present (winter) so that might be a summer time job.

I hope that this helps

 

[spikemd]

My fusebox looks similar, but not as bad. It has one small (0.5) crack and the leads on the relay and in th fuse box look good, they are not black or corroded. That is why my first step will be new relays before jumping into replacing the fusebox. I was hoping to 'upgrade' the relays if they don't fry anything else.

I am going to try and take a look at the blower motors today to be sure they are spinning well.

 

[johnnywadd]

BEST BET : Replace the fusebox, I had the same problems and kept blowing relays and other problems. Once the Fuse box is damaged like that relays just don't make good contact anymore plus in my opinion its a fire hazard. Replaced mine (very easy to do) with a replacement from Atlantic British for around $260.00 two months ago and it solved a lot of problems.

Johnny