Will it help to install a puller fan on the back side of the AC condensor between the condensor and radiator? Iam trying to keep the condensor cooler to reduce head pressure on the compressor at idleing speed.

Will it help to install a puller fan on the back side of the AC condensor between the condensor and radiator? Iam trying to keep the condensor cooler to reduce head pressure on the compressor at idleing speed.
It will help if you install a larger than 3000 cfm puller fully shrouded behind the radiator.The condenser is close enough to the radiator to benefit from the airflow at idle provided by the large puller.If you have a mechanical fan..the same applys.A fullyshrouded functional mechanical fan should flow enough air to cool both the condenser and the engine rad.Stay away from auxillary pusher fans..they pin wheel air..are 20% less efficient and act as a restriction before the core on the road.FWIW..if head pressure is a concern,you may be overcharged.recover and weigh and recharge to spec.

Thanks !!

I just installed a new fan and clutch. Maybe that will help.

I just installed a new fan and clutch. Maybe that will help.

The new fan and clutch work in tandem with a full shroud.You want to pull on the total surface area of the core for maximum effiency.Anything less will have the clutch type fan pulling air up and around and not moving thru the core.The fan blades at rest should have them 1/2 in and 1/2 out of the shroud exit.The better you seal the shroud to the core will result in more airflow thru the rad and the condenser.Let us know how your new combo pans out.:)

Stay away from auxillary pusher fans..they pin wheel air..are 20% less efficient and act as a restriction before the core on the road.

I hate to be the bearer of bad news....or good news in this case... but this poster is misinformed or something? There are many contemporary OEM applications that utilize this technology for exactly that application(s). From Volvo to BMW to Mercedes to even Camaros... they all do this....uses up front aux fans.. and have been for years. Take a peak into a grill of a BMW X7 sometime and see the huge aux fan that's mounted.

And... because they have unabated frontal attachment methods.... the purported "blocked" or "impeded" airflow simply flows around the fans and causes no appreciable "blockage" at all. Are they less efficient than "pullers"? Yes.. but not a huge deal per se.

Aux fans are a great way to help general cooling and air conditioning.

I havent determined if I will add the electric fan or not. Seems like it would really help in slow traffic situations.

I converted a 1990 GMC to R134 and because of heat the pressure was to high. We installed two 12" pusher fans to the condenser and have not had any problems since. Just my .02 worth.

I hate to be the bearer of bad news....or good news in this case... but this poster is misinformed or something? There are many contemporary OEM applications that utilize this technology for exactly that application(s). From Volvo to BMW to Mercedes to even Camaros... they all do this....uses up front aux fans.. and have been for years. Take a peak into a grill of a BMW X7 sometime and see the huge aux fan that's mounted.

And... because they have unabated frontal attachment methods.... the purported "blocked" or "impeded" airflow simply flows around the fans and causes no appreciable "blockage" at all. Are they less efficient than "pullers"? Yes.. but not a huge deal per se.

Aux fans are a great way to help general cooling and air conditioning.

Correct..the OEM.s use aux pusher fans.Thank you,I am now informed.They also apply bandaid fixes when the left hand does not communicate with the right.Ever heard of a service bulletin released after a vehicle launch?Oops..we screwed up,not enough cfm thru the cores from the pullers.Heres the bandaid fix..mount a pusher.I stand pat..a 3300 cfm shrouded puller covering 90% of the core should move enough air thru the ac condenser when mounted correctly to keep head pressure in check.Dual pullers,pcm controlled high and low speed relays,WOT clutch disengage etc etc hardly apply to a 1st gen F body.I am a fan of dual fans and dual relays with an ac input.Installed correctly..there is no need for a quick fix pusher.

Dual pullers,pcm controlled high and low speed relays,WOT clutch disengage etc etc hardly apply to a 1st gen F body.

but... that's exactly the setup I'm running on my '68!

The dual-fan/dual-speed/three-relay setup would actually work fine without a PCM or other controller--just use two temp sensors in place of the PCM outputs. This is based on '99 Z28 wiring, but it'll adapt to any dual-fan setup:


Relay FAN1 – Left fan
Terminal 85 Hot in start or run
Terminal 86 To pin J of connector C100 (or low-temp switch)
Terminal 30 To 20A fuse and battery voltage
Terminal 87 To Left cooling Fan pin B

Relay FAN2 – Right fan
Terminal 85 Hot in start or run
Terminal 86 To pin H of connector C100 (or high-temp switch) AND Terminal 86 of FAN3 relay
Terminal 30 To 20A fuse and battery voltage
Terminal 87 To Right cooling Fan pin B AND Terminal 87a of FAN3 relay

Relay FAN3 – speed control
Terminal 85 Hot in start or run
Terminal 86 To pin H of connector C100 (or high-temp switch) AND Terminal 86 of FAN2 relay
Terminal 30 To Left cooling Fan pin A
Terminal 87 To 20A Ground
Terminal 87a To Right cooling Fan pin B AND Terminal 87 of FAN2 relay

(and Right cooling Fan pin A to 20A Ground)


http://www.blown.net/ls1swap/help/ls1_coolingfans_rodder.jpg

Correct..the OEM.s use aux pusher fans.Thank you,I am now informed.They also apply bandaid fixes when the left hand does not communicate with the right.Ever heard of a service bulletin released after a vehicle launch?Oops..we screwed up,not enough cfm thru the cores from the pullers.Heres the bandaid fix..mount a pusher.

Wow.. I understand your point about OEMs.. but for the most part companies such as Mercedes, Volvo, BMW and yes... even GM use aux (pusher) fans prolifically.. so these are not a "bandaid" fix by any means but defacto standards. In fact, there are very good high capacity industrial coolers that push air instead of pull. The efficiencies are similar with "open shrouded and/or non-shrouded fans! I know.. because I have designed industrial applications for nuclear use. Same in automotive.

I stand pat..a 3300 cfm shrouded puller covering 90% of the core should move enough air thru the ac condenser when mounted correctly to keep head pressure in check. I am a fan of dual fans and dual relays with an ac input.Installed correctly

I agree with you here. I would rather do this too. But, what I am saying is there is nothing wrong with the other either..

I agree with you here. I would rather do this too. But, what I am saying is there is nothing wrong with the other either..

Hotrod..I agree with you whole heartidly.There is nothing wrong with installing an aux pusher fan if need be.I just prefer to use a dual fan/relay setup with an ac on input to keep clutter and additional hardware out of the engine bay.The above poster has a nice schematic showing how you can upgrade the 1st gen F body wiring harness to accomodate multiple relays.Hope all this helps the original poster with his question.:beers:

What about putting a black magic fan as a puller between the condensor and radiator?

What about putting a black magic fan as a puller between the condensor and radiator?

First off..just how far away is the condenser from the rad?The condenser should be close enough to the rad to benefit from the primary coolant fan.To far forward would have the condenser cooled only with vehicle speed and not at rest at idle with the primary fan pulling around..but not thru the condenser.

The condensor is about 2 and a half inches from the radiator. I have the stock shroud on the radiator.There is a small gap at the top between the radiator and condensor. That may cause a little airflow loss. But thats the way gm made it.

67..sounds like your stock setup should be sufficient enough to draw air thru the condenser.Dave posted that he cured his head pressure issue with a pusher fan.This would be the way to go vs installing a puller between the condenser and rad even if it would fit with only 2.5 inches.If you have done everything possible to pull with your primary fan..then an aux pusher (as stated previously) is a cost effective remedy and will help move more air thru the condenser at low vehicle speed.Make sure you are not overcharged.With refrigerant..more is not always better if its exceeds the recommended capacity as suggested by the manufacturer.(sp).

Thanks !