Aux fan, push or pull?

[CyFi6]

My A/C specialists told me that i should add an auxiliary fan to the condenser to improve the idle performance. I understand that some supras came stock with pusher fans, its a little unclear which ones exactly, but mine doesn't have one. I live in AZ (California car) so it could use all the help it could get. I bought an electric fan that is reversible so i can set it up as push or pull, but i understand a pull setup is much more efficient. My fan is about 2.5" thick, and i think it might fit between the condenser and radiator, if it does, would that be a better place to put it, or would it be better to put it up front and set it up as a pusher? Thanks for any tips.

 

[IBoughtASupra]

Between the condensor and radiator, pull is good. In front the condensor, pusher is good.

If you reversed the ways I told you, you will be working against the stock clutch fan which is not a goof ideal.

 

[CyFi6]

No, I understand that, but what im asking is which would be better, having it set up to push, in front of the condenser, or pull, behind the condenser/in front of the radiator.

 

[grimreaper]

its not going to be easy to make drastic improvements at idle. I HAD an extra pusher on the cond. Waste of time and saw no temp drops at the center vent.

 

[GrimJack]

its not going to be easy to make drastic improvements at idle. I HAD an extra pusher on the cond. Waste of time and saw no temp drops at the center vent.

That's not where you would see an improvement anyway. The AC system can only put out air at a certain temp - any lower, and it will suffer from icing, which will fubar the system. The key is how much work the compressor has to do, and the way to measure that would be to check how much time the compressor spends off vs how much time it's on.

For the OP: Pull fans are the best as long as you have a shroud. If you're running shroudless, set it up as a pusher. It won't work as well, but it's still better than nothing.

Supras have come with both setups... pushers setup in front of the condenser, as well as pullers set up behind the radiator. Although I've never seen one with both.

 

[CyFi6]

That's not where you would see an improvement anyway. The AC system can only put out air at a certain temp - any lower, and it will suffer from icing, which will fubar the system. The key is how much work the compressor has to do, and the way to measure that would be to check how much time the compressor spends off vs how much time it's on.

I dont know of any supra that will put out ~38 deg. vent temperatures at idle in the heat, if yours does wonderful but mine is fully serviced and brought to spec and vent temps rise at idle, so im trying to add some extra airflow to allow more liquid refrigerant to the expansion valve.

Anyways, when you say if the fan has a shroud use it as pull but if not use it as push, why so? is there a disadvantage to setting it up as a pull behind the condenser (in front of the radiator)? Just to clarify, i have a fan shroud on my clutch fan, but the electric fan is a single fan, no shroud around it other than the grill.

 

[GrimJack]

I dont know of any supra that will put out ~38 deg. vent temperatures at idle in the heat, if yours does wonderful but mine is fully serviced and brought to spec and vent temps rise at idle, so im trying to add some extra airflow to allow more liquid refrigerant to the expansion valve.

Anyways, when you say if the fan has a shroud use it as pull but if not use it as push, why so? is there a disadvantage to setting it up as a pull behind the condenser (in front of the radiator)? Just to clarify, i have a fan shroud on my clutch fan, but the electric fan is a single fan, no shroud around it other than the grill.

Well, mine may work fine in the heat, however, my definition of heat probably doesn't match yours. I live on the west coast of Canada, with max temps at under 30C for the most part, and that really rarely. You live in Arizona, where you can fry an egg in the palm of your hand if you're actually in the sun, which happens for about 26 hours each day from what I gather.

I've never seen one mounted between the rad and condenser - to be honest, I'm surprised anything will fit in there. How are you going to tell if it breaks? My statement above was somewhat inaccurate, I guess - knowledge gleaned from years of experience attempting to overclock computers has shown me that pull fans with shrouds work best. Push fans with shrouds work somewhat less effectively, and when you remove the shroud, they seem to work equally poorly in either configuration. What I should have said is, if you don't have a shroud, put it in either spot!

 

[CyFi6]

Ah i see. Im still not completely sure if it will fit between the condenser and radiator yet, though there seemed to be quite a bit of room when i last looked. If there's enough room i will probably put it there, if not, obviously i will set it up as a pusher. Thanks.

 

[grimreaper]

never had the evap coil sensor kick off the condenser in 105*ambient at idle. Vent temps always stuck to low 50's high 40's until I started moving again . The fan helped the hi/low pressures but it still heat soaked just a tad bit slower. I went through a good bit of work making that extra fan fit in the nose. It was placed squarely against the condenser coil as a pusher. The results were not worth the time IMHO. I found a steady 1500rpms in longer stop and go situations to be much more beneficial.

 

[JonnyZ(Socal)]

I would go with pull... and you only need a shroud if the fan is farther than an inch from the condenser, this is what I was taught at UTI!

 

[CyFi6]

never had the evap coil sensor kick off the condenser in 105*ambient at idle. Vent temps always stuck to low 50's high 40's until I started moving again . The fan helped the hi/low pressures but it still heat soaked just a tad bit slower. I went through a good bit of work making that extra fan fit in the nose. It was placed squarely against the condenser coil as a pusher. The results were not worth the time IMHO. I found a steady 1500rpms in longer stop and go situations to be much more beneficial.

Ya im not expecting to gain too much. I would be happy with 50 degree temps at idle (blower on high) but its just not happening. Im not expecting to get too much help out of the fan, but the AC place recommended i try that (they are a highly respected place here in AZ) so i will try that, if that doesn't help i will have them do some more diagnosis.

I would go with pull... and you only need a shroud if the fan is farther than an inch from the condenser, this is what I was taught at UTI!

OK thanks for the tip, hopefully it fits in there.

 

[Poodles]

In reality if you put it in between you're making it a push AND pull fan, which may cause issues. As your real goal is to cool the condensor, I'd mount it in front of it.

 

[CyFi6]

In reality if you put it in between you're making it a push AND pull fan, which may cause issues. As your real goal is to cool the condenser, I'd mount it in front of it.

Thats pretty much why i was asking, because i wasn't sure if that would make it less effective than just being a push in the first place. Anyways it barely didn't fit in-between, so i put it in front.

 

[IBoughtASupra]

On most cars we do A/C service, we tend to change the Evap dryer since they get clogged over the years and especially on a 20+ year old car.

We did an Accord last month and to get it colder we changed the dryer. It was freezing after changing the dryer on a 95 degree day.

We have done it many times especially after adding refridgerant and people saying it is not cold enough.

 

[3p141592654]

I think you will find you are compressor limited at idle, rather than condenser limited. Compute the super heat to confirm. The super-heat will be too high (should be 3-5 deg usually), and the TXV valve in the evaporator will be wide open but lack of flow will prevent it from coming down to where it should be.