motorgeek.com :: Socially inappropriate motoring information.
Search this topic:
motorgeek.com :: Board index :: The Tech Lounge :: Engines
Post new topic Reply to topic  [ 14 posts ] 

How much airflow does the A/C radiator really block?

Author Message
 Post subject: How much airflow does the A/C radiator really block?
PostPosted: Sun Jun 14, 2020 11:34 am 
Offline
kickin' tires'n lightin fires
User avatar

Joined: Wed Mar 30, 2005 3:29 pm
Posts: 692
Location: NorCal
So I boiled over my coolant for the first time after a spirited drive up my local steeps the other day. Coolant got to about 104 then started steaming. My question is how much of an increase in cooling could I expect from simply removing the A/C radiator to allow for better flow onto the engine radiator? I don't have the A/C compressor hooked up, or the system charged (it was a project for down the road) and I've got the upgraded radiator from 034. At this point basically contemplating if it's even worth it to keep the prospect of A/C, or perhaps there's a smaller A/C radiator I could relocate so it's not hogging all the airflow...thoughts?

For reference the car is IIc at about 300whp. The ascent was about 5 miles but low ambient temperatures. Thanks in advance!

_________________
CJ Leydig
'89 90 20vT Quattro (The Fun)
'91 Jetta GLI (The Daily)


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Sun Jun 14, 2020 1:40 pm 
Offline
mach 2 with my hair on fire
User avatar

Joined: Wed May 25, 2011 7:56 am
Posts: 1335
Location: Cincinnati, Ohio
what fan do you have? 7A or the bigger version?

_________________
CURRENT
1994 Cabriolet - 5 speed - 1995 90Q 20VT
- 1987 Porsche 924S - 1986 Audi Coupe GT

PAST
1993 Audi 90 CS Quattro - 1990 CQ - V8 - 1995.5 Audi S6 - 1993 Audi V8 - 2013 A5 Prestige - 2011 A4 Avant


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Sun Jun 14, 2020 9:16 pm 
Offline
kickin' tires'n lightin fires
User avatar

Joined: Wed Mar 30, 2005 3:29 pm
Posts: 692
Location: NorCal
I’ve got the rs2 shroud/fan combo. Seems like the engineers should have put the radiator in front of the a/c condenser

_________________
CJ Leydig
'89 90 20vT Quattro (The Fun)
'91 Jetta GLI (The Daily)


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Mon Jun 15, 2020 6:51 am 
Offline
I post, therefore I am
User avatar

Joined: Thu Mar 12, 2009 10:42 pm
Posts: 3974
Location: Lost Angels, Ca
do you have proper ducting?

_________________
¯\_(ツ)_/¯
Image


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Tue Jun 16, 2020 2:36 pm 
Offline
kickin' tires'n lightin fires
User avatar

Joined: Wed Mar 30, 2005 3:29 pm
Posts: 692
Location: NorCal
Sure do.

Has anyone measured a drop in average temperature by removing the condenser?

_________________
CJ Leydig
'89 90 20vT Quattro (The Fun)
'91 Jetta GLI (The Daily)


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Tue Jun 16, 2020 3:11 pm 
Offline
I post, therefore I am
User avatar

Joined: Thu Mar 12, 2009 10:42 pm
Posts: 3974
Location: Lost Angels, Ca
the rs2 fan move close to 8000 cfm. with a proper ducting, cooling system it shouldnt be a problem.
also make sure if you have a lower temp. thermostat, you will use the corresponding lower temp fan switch as well

_________________
¯\_(ツ)_/¯
Image


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Tue Jun 16, 2020 11:27 pm 
Offline
kickin' tires'n lightin fires
User avatar

Joined: Wed Mar 30, 2005 3:29 pm
Posts: 692
Location: NorCal
Well the ducting is all original, but there are no glaring holes. That's a good point on the thermostat, I'm not sure if I've got a lower temp one in there, or the lower-temp fan switch - might it be worthwhile to swap those in so the fan turns on earlier. Around what temp should low speed come on?

On an interesting note the low speed fuse (20a) is blown, but not the high one (60a) - I wonder if that might have something to do with it. Fan may not have come on until temps are high. Could be my low-speed resistor being shot. Any idea on what the draw is for an RS2 fan, even at low speed? It's high current is the reason I didn't use stock fuse setup.

_________________
CJ Leydig
'89 90 20vT Quattro (The Fun)
'91 Jetta GLI (The Daily)


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Wed Jun 17, 2020 9:35 am 
Offline
kickin' tires'n lightin fires

Joined: Sat Jan 14, 2006 12:50 am
Posts: 614
Ummm, yeah that's your problem. You have that wired up properly?

Once these get hot they're difficult to cool down. You'll want to fix the low speed ASAP. I'd leave the A/C Condenser (not radiator) alone and fix the route of the problem.


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Wed Jun 17, 2020 2:16 pm 
Offline
kickin' tires'n lightin fires
User avatar

Joined: Wed Mar 30, 2005 3:29 pm
Posts: 692
Location: NorCal
I'll need to go back to the wiring drawing board for that one, as I did modify the rad fan wiring with a high amp (60a)relay/breaker for the extra draw of the RS2 fan, but only for the high speed circuit. For the low speed of the RS2 fan, I used the stock 30a high speed circuit (that fuse is not broken). Perhaps I should lower the fan temp sensor...

I see there's different temp fan kick-ins, all the way down to 75-82 (next up is 87-92 for 3 pin), but given I live in California, is there any reason not to choose the lowest temp? I'll measure if the fan is kicking on at the right time.

_________________
CJ Leydig
'89 90 20vT Quattro (The Fun)
'91 Jetta GLI (The Daily)


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Thu Jun 18, 2020 5:44 am 
Offline
mach 2 with my hair on fire
User avatar

Joined: Tue Mar 16, 2004 12:41 pm
Posts: 1885
Location: Chelmsford MA
if your radiator has no blockages, you retained the shrouds & ducting, and the fan is properly wired you shouldn't have issues

_________________
1995 S6 Sedan Cashmere/Anthricite
1995.5 S6 Avant, Silver/Platinum
1993 S4 Black/Anthricite & Carbon
1991 Coupe Q Silver/Black (perpetual eS2 project)
1991 Coupe Q Silver/Platinum
1991 Coupe Q Pearl/Black Shell

http://www.naaclub.org


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Thu Jun 18, 2020 11:08 am 
Offline
kickin' tires'n lightin fires
User avatar

Joined: Wed Mar 30, 2005 3:29 pm
Posts: 692
Location: NorCal
audiPete wrote:
if your radiator has no blockages, you retained the shrouds & ducting, and the fan is properly wired you shouldn't have issues

To play the advocate the A/C rad does directly block the engine rad :D

Just idling the car and getting it upto temperature the coolant is circulating (I see it coming back into the reservoir, what are the signs of a blockage?) but now the fan isn't coming on at all (post boil-over).

I noted it seemed to be running a little warmer than usual before boiling over so I'm replacing the fan switch as a starting point. Fuses are all in tact, and the fan motor can be jumped. Looking at another thread I think it's a good idea to get that low speed wired into a manual switch though...

_________________
CJ Leydig
'89 90 20vT Quattro (The Fun)
'91 Jetta GLI (The Daily)


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Thu Jun 18, 2020 11:14 am 
Offline
mach 2 with my hair on fire
User avatar

Joined: Tue Mar 16, 2004 12:41 pm
Posts: 1885
Location: Chelmsford MA
in the stock system, on both the automatic and manual CCs, I believe that turning on the AC automatically also turns the fan on to low speed.

_________________
1995 S6 Sedan Cashmere/Anthricite
1995.5 S6 Avant, Silver/Platinum
1993 S4 Black/Anthricite & Carbon
1991 Coupe Q Silver/Black (perpetual eS2 project)
1991 Coupe Q Silver/Platinum
1991 Coupe Q Pearl/Black Shell

http://www.naaclub.org


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Thu Jun 18, 2020 8:44 pm 
Offline
I post, therefore I am
User avatar

Joined: Thu Mar 12, 2009 10:42 pm
Posts: 3974
Location: Lost Angels, Ca
audiPete wrote:
in the stock system, on both the automatic and manual CCs, I believe that turning on the AC automatically also turns the fan on to low speed.


more like medium speed. low speed is with after-run.

_________________
¯\_(ツ)_/¯
Image


Top
 Profile  
Reply with quote  
 Post subject: Re: How much airflow does the A/C radiator really block?
PostPosted: Tue Jun 23, 2020 11:39 pm 
Offline
kickin' tires'n lightin fires
User avatar

Joined: Wed Mar 30, 2005 3:29 pm
Posts: 692
Location: NorCal
Well replacement switch fixed the issue. I had been running a colder 75/83 switch, now 87/94, and given my thermostat temp I think it was always running on high

_________________
CJ Leydig
'89 90 20vT Quattro (The Fun)
'91 Jetta GLI (The Daily)


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 14 posts ] 
Search this topic:
motorgeek.com :: Board index :: The Tech Lounge :: Engines

Jump to:  



Information

Users browsing this forum: Google [Bot] and 3 guests



You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum
cron
  |  It is currently Sun Aug 09, 2020 2:12 am
Share |