Help - 97 4.6

[NVRover]

I've posted this question on a couple of other BBS, so my apologies if you're seeing this multiple times. Anyway...

Recently I noticed a high pitched, rapid, "rattling" (for lack of better adjective) sound coming from the front of the engine compartment in my 97 4.6. I thought it may be the water pump, power steering pump, or something similar, however when I stuck my head under the hood I noticed it was coming from in front of the radiator just behind the grille. I see the two fans but I don't know what would cause this sound. These aren't the same fans as the viscous fan and drive. Both fans seem to work. Last night in stand still traffic the truck began to "over heat". The temperature guage needle went to the white line just before the red H area.

I also noticed that our A/C wasn't working as well and the HVAC display showed a book symbol and exclamation point. I turned the A/C off and the temp guage returned to a somewhat normal reading (slightly hotter than center).

Any ideas what could be causing this? Thanks in advance for any help you can offer!!

Chris

 

[RVRSRVC]

Chris,
I'd be willing to bet that the two symptoms are related! The two electric fans are used to supply ambient air over the ac condensor, and subsequently the radiator, to allow the refrigerant to exchange heat properly. If the noise is caused by a failing fan motor or an obstruction in the fan blades, the temperatures/pressures of the coolant and the refrigerant will not be functioning well.
The fact that the engine temperature settled down when the a/c was turned off was probably a result of removing the additional heat of the a/c system from the engine's cooling system.
The a/c head unit has an ability to self-diagnose and illuminate the open-book warning symbol. There is a sensor that measures coolant temp for a comparative reading on the climate control. That is one of the ways that it knows to shut down the compressor to ease the burden on the engine.
Also, if after you resolve the temp issues, and find that the a/c still doesn't stay cold around town, there is a shim under the compressor clutch that probably needs to be removed. If you need more info on that, just let me know.
(My apologies if you already know this stuff!)
If you find that you are in need of replacement fans, I have a set from a 97 4.6. We had to replace the condensor on that vehicle and the new condensor came with new fans. We fitted the new fans of course, but her old ones only had about 20k miles on them.

Don't let this go on for to long. The engines are not that tolerant of continued overheating/running hot.

Trevor Griffiths
Treasured Motorcar Services
Reisterstown, Maryland

 

[NVRover]

Trevor, thanks for the reply. Your information was very helpful and confirmed what I had learned after I posted this message. How do I contact you regarding those fans. After I narrowed it down to those condenser fans I began looking for replacements. As you well know I can not buy replacement fans by themselves from the aftermarket parts dealers. The LR Dealer in Vegas claims they can get the fans, but my mechanic is skeptical. If I can get the used fans from you cheaper than the new ones through the LR Dealer, that would be great. Just let me know how to contact you. Thanks again for your assistance, I appreciate it.

Chris

 

[Steve83]

Pop the cover off the engine fuse block and look at the 2 yellow relays at the RHF corner. If they're toasty brown on the sides, you need a new fuse block & about 4 yellow relays. You might also benefit from the A/C clutch link lead kit & the alternator link lead kit.