Adding 3 fans to rear A/C condenser

[mthomas58]

Working on my wiring plan for a three 7.5" Spal pull fan add to the underside of my rear A/C condenser. Three 7.5" fans will cover the entire surface area & will fit in this tight space. Will be adding relays wired directly to the + on the comperssor to turn the fans on/off. Planning on running a new hot lead direct from the battery to power the fans with inline fuses. Each fan is rated at 7.5amps and pull 440 CFM.

Need suggestions for getting power to the fans.

Best route to run a positive lead from the battery to the engine compartment?

If I run a cable into/through the cabin, can I get to the engine compartment through the tunnel opening on the floor between the rear seats?

Thanks!

[mthomas58]

Anyone have any experience running a new Pos lead from the battery to the engine compartment?

Thanks!

[curiousone940]

I did a similar project on my '89 and used one of the empty slots in the fuse box in the engine compartment....no need to run a dedicated wire all the way to the battery itself.

[mthomas58]

Great idea. I've got three open fuse slots, but didn't know if it would be OK to use. Glad I asked. Problem solved.

Thanks!

[BReyes]

Are you running barrier hoses? Have you thought about a pro-cooler (front ac condensor) to lower your vent temps?

My 69 has fans on the rear condensor too.

[scottb]

How are you going to fit the fans? Do you have a turbo tail?

Have you considered switching the fans off of the same wire that switches the compressor?

[masraum]

You do realize that there's a huge fan sucking air through the condenser, right. The only time the three fans are likely to help is when you are at idle.

[scottb]

Originally posted by masraum
You do realize that there's a huge fan sucking air through the condenser, right. The only time the three fans are likely to help is when you are at idle.

I'd love to see some empirical data on whether fans on the rear condenser actually help. Some on this BBS swear that they help. I'm skeptical.

[AvonGil]

I agree if anything, the one in the middle would probably be a waste even at idle.

[mthomas58]

No barrier hoses, although I replaced two of the three hoses this summer along with the rear condenser, drier, ft condenser motor and evaporater motor. $1,900 later I got my vent temps down to the mid 30's to low 40's. I'm convinced that the greater the airflow created through the undersized and poorly placed condensers, the better.

And, yea I've got tail! ....with the notched condenser for the rear wiper.

[scottb]

IMHO, your time and money would be better spent putting a condenser and fan in the front left fender.

[masraum]

If you've got a tail then you are getting even more air at speed than a car with no tail. So you are getting temps in the 30s and that's not enough. I'm guessing that you need another condenser.

[mthomas58]

I'm thinking my stock A/C system that is now fully operational will be OK. But with a little tweeking (i.e. relatively low cost fan add) I can improve its efficiency. In stop and go traffic my vent temps go from the mid 30's to the low-mid 40's at a standstill then back down when I get moving and get air flow back up. I'm hoping the fans will lower the high end of my vent temp range. Make sense?

[masraum]

Sure, like I said, the only time the fans will help is when in stop and go. Is the fan for your front condenser working?

[mthomas58]

Steve, this car is my daily driver. Call me a little obsessed but very unpleasant memories from this summer linger (trying to get my system working). I'm sure you can relate. The only city I've lived in hotter and more humid than Atlanta or Tampa is Houston.

[mthomas58]

Yep, front condenser motor and evap motor were both fried and were replaced.

[masraum]

Originally posted by mthomas58
Steve, this car is my daily driver. Call me a little obsessed but very unpleasant memories from this summer linger (trying to get my system working). I'm sure you can relate. The only city I've lived in hotter and more humid than Atlanta or Tampa is Houston.

Funny, I've lived in Tampa too, so yes, I understand about heat. At least you have an '87 so you have the updated vents. Something needs to be done to the center vents to allow them to both point at the driver, and the far left vent should be closed. I'd guess that the fans should definitely help in stop and go. Good luck.

[Jim Sims]

Install a trinary pressure switch in the discharge line of the compressor. In addition to having high and low pressure cutouts (opening contacts) it has an extra set of contacts that close at intermediate pressures (such as when the deck lid condenser loses effectiveness due to lack of air flow). This extra set of contacts can be used to energize either the fans directly or through a relay.

Vent air temperatures below 35F are not really very useful as they indicate the evaporator is at or below 32F and it will ice up and block air flow. If you're at 40F or below and need more "cooling", work on improving the air flow through the evaporator, dash and around the interior of the car.

[Jack Olsen]

What's your source on the fans?

[mthomas58]

Jack, my fan source is The Fan Man......$53 each for 7.5" spals. Best pricing I found.

http://www.the-fan-man.com/shop/size-pull-part-0358-p-179.html?cPath=33

Thanks!