AC pusher fan for condensor

[tbrumm]

Well, I am trying to do some things to improve the ac performace in my truck. I have read several threads that mention installing a pusher fan in front of the AC condensor. My truck's ac does okay but nor great (at 85°, duct temps will get down to about 65°) running down the highway, but as soon as I am down to 25mph in town (or sitting in traffic UGH!) the temps climb rapidly. I am thinking a pusher fan may help that situation. I know others have done this, but what is a good brand and model of fan to use? Can I just mount it directly to the condensor with the "zip tie" type kits, or would it be better to fab up some mounts to the radiator support? I know I will need a relay, and was thinking of triggering it when the system is set to MAX AC. I don't want to trigger ot off the compressor as it seems like the compressor runs all the time with the AC on. I should mention that me truck as "dealer installed" ac with a Seltec compressor and a parallel flow condensor and is not the Ford system. I had the system evac'd, leak checked and new oil and refrigerant put in (and the shop says it is as "good as it is gonna get") It has an expansion valve in front of the evaporator and a filter/drier mounted in front by the condensor. I have some aluminum faced foam insualtion ordered for the evap housing too. Thanks for any suggestions!

 

[firehawk]

Check your pressures, as a low charge can produce these symptoms.

 

[laserjock]

^^^ Thought the same thing.

 

[tbrumm]

Thanks, guys. I will get soem gauges and check pressures. Just I had a shop do the work doesn't mean they did it right does it. Still wondering if anybody is running pusher fan on the condensor too.

 

[lotzagoodstuff]

Going down the road you are putting plenty of air accross the condenser, you should be cooler than 65 degrees. +1 on checking your refrigerant pressures as it sounds like you need a charge.

 

[Wyreth]

Everyone is right, even without a pusher you should have better AC performance than that. However for me, it's on the short list of things to do this summer, because anytime I hit traffic in the Vegas heat... My duct temps would go from 50ish to about 80ish, and with the mouse cough these trucks call a blower fan, that's.... uncomfortable when it's 120 outside and the sun is RIGHT THE F' THERE!

Myself I would start by looking into and what is currently amis with your system. Also look into installing a heater bypass valve, as shutting off the hot water through the heatercore will also drastically improve duct temps. Especially if your blend door is no longer sealing properly.... and it's not, trust me. After you have that, then I think it would be time to look into a pusher fan. As far as make or model, I would simply trudge through the pick and pull until I found a pusher that looked the right size. But that's me, and hopefully others will chime in with a specific one that is perfect.

As far as mounting, yes, I am sure you could use zip ties to mount it, and make it work well too. But really, do it right. Fab a real mount. =P

 

[chris142]

I live in the desert and on a 100+ day I see 40f vent temps so something is definatly wrong with yours. One thing that comes to mind besides the obvious is a vacuum leak. There is a vacuum hose near the passenger side hood hinge that rots and leaks vacuum. When it leaks vacuum the dash does not work right and wont cool very well.

Do you have a frost line back to the compressor? What kind of refrigerant are you using?

 

[Sycostang67]

I just had my system evac'd and reloaded today. I'm running a factory setup converted to 134. I am blowing 60* and idle and 45* while moving. You may even take it to another shop to have the guages thrown on and your pressure checked, they may do it for free.

I need to look into the water cutoff, that sounds like it might get me a few degrees cooler as well.

 

[chris142]

Did they change the dryer and put an orifice tube with a smaller orifice in it? As well as 2.75 lbs of r134a? If so you may have a weak compressor that's not pumping well at low rpm's

 

[whalebus]

Mine sits about at 50 degrees. I have added and taken out freon and its still the same. What do your pressures look like?

 

[tbrumm]

Yeah, I'll have to get some gauges on the system and see what pressures are at. I'll see if I can borrow some gauges. After the shop evac'd the system and leaked checked it, they told me they put in 2-3/4 lbs of R134a. They also installed a new expansion valve (that was supposed to correct for an R134a system). A new parallel flow condensor was also installed at the same time becuase they found a leak in the old one. When I complained about the fact that the system didn't seem to be cooling very well, they added another 1/4lb of R134a to bring the total to 3lbs. and told me it was as good as it was going to get. If I understand correctly, the dealer installed system on my truck does not have an orifice tube like the factory setup. It also has a filter/drier mounted up front by the condensor, rather than the accumulator mounted by the evap housing like the factory system. It could be that the compressor is getting tired, although it isn't noisy. The duct temp does drop a little with higher rpms. I do have the heater shut off valve installed and that closes when the system is set to MaxAC. Thanks for the suggestions, guys. I'll try and get some gauges and see what the pressures are. I don't want to take it back to the shop that did the work because I was not impressed, and I can't afford for them to keep throwing parts at the system without results. According to the shop, the system is not leaking and is functioning.

 

[redstang410]

Make sure the vent that blocks off outside air is properly closed.
Sometimes they stay stuck open and you end up cooling hot outside air instead of recirculating the cooler cab air.
Always use the max a/c position on the controls. That positions is suposed to recirculate only cab air.
Norm a/c sucks air from the outside cowl.

 

[Oog]

Look at older Benzes for big pusher fans. BMW too, but theirs tend to be smaller.

One other cool thing of the Benz is the auxiliary water pump.

I plumbed mine inline to the heater core, and when camping, I can shut down the truck, run the blower on low and turn on the aux. water pump. It'll circulate coolant through the block providing an extra 2-3 hours of warmth as opposed to only 30 minutes.

 

[chris142]

Oh I see. The add on AC units usually use less refrigerant than the factory air did. I bet it's overcharged. Get some guages and get me the pressures. You want it to be around 2.2x ambient temp on the high side.

If it's 90 out you want to see around 198psi. And never more than 2.5x ambient which would be 225 @ 90 ambient.

 

[tbrumm]

I appreciate all the suggestions guys. I finally got some good gauges and had some time to do some checking this weekend. Just a few more notes about my system in particular. The shop that worked on my truck did not replace the filter/drier which is mounted up front by the condensor. The filter/drier does have a sight glass, which I cleaned, but really can't see anything in there. The refrigerant is 134a. I do have the heater cut off installed and that shuts off the water flow to the core when the system is set at MaxAC. The door in the plenum that shuts off the outside air flow in order to recirc inside air does appear to be closing as you can hear it "thunk" closed when setting the knob to MaxAC. Vacuum lines seem to be in good condition and I don't hear any leaks or see any deteriorated vac hose. I also checked the drain hole in the evap housing and may have found part of my problem. I noticed it was dripping but wasn't drippping much. I stuck a wire up in there and took a shower! A lot of water drained out of there - that could not have been helping the cooling! Isn't it amazing how simple stuff like that can get ya. I then hooked up the gauges. It is about 80° here today. With the truck cold and shut off: low=82/High 82. I then started the truck and at high idle and the system still cold the low=8/high/120. After 10 minutes run time and revving the engine to 1800 the low dropped into vacuum at -2 and high dropped to 105. Going back to idle , the low went back to 18 and high to 150. Vent temp went as low as 60°. This is just with the truck sitting in my driveway with no electric fan blowing over the condensor. Revving the truck again after about 5 minuted to about 1800, the low was 4 and high 160. Returning to idle, the low was 18 and high 155. The high side line at the compressor is very hot with the low side line only slightly cool. The expansion valve at the evaporator is pretty darn cold and sweating. I hape I have provided enough info - I appreciate any help you guys can offer, Thanks - Todd