Radiator fan(s) / Thermostat Questions - GM Forum - Buick, Cadillac, Olds, GMC & Pontiac chat

1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Radiator fan(s) / Thermostat Questions

Reply

 
 
 
Old 08-05-2005, 02:45 PM
  #1  
Junior Member
Thread Starter
 
Join Date: Aug 2005
Location: Waldorf, MD
Posts: 3
Thanks: 0
Thanked 0 Times in 0 Posts
w3lzx is on a distinguished road
Default Radiator fan(*) / Thermostat Questions

Hello All,
Just bought a used 97 3.8 SE FBI Bonny with 103,870 miles on it.
All fluid levels were fine, Engine runs great, shifts great, A/C works great. Looked in the oil intake and springs and all were nice and shiny. Alarm is a pain though, I think I am getting out the snips.
I'm gonna change the oil, change tranny filter, and flush coolant and wanted to put in a 180 thermostat.
Coolant looked a little mucky on underside edges of cap and on edges of reservoir.
I do not have the owners manual or a Chiltons manual yet.
Two questions:
1. There are two radiator fans.
The drivers side seems to work normal.
The other is on the Passenger'* side of the radiator and does not seem to come
on, I would think it should come on with the air conditioning (right or wrong). If it
should, what could be the problem?
2. Is there anything that may be "tuned" to work off the stock thermostat that will
be adversely affected by putting in a 180 thermostat?
Thanks, Bob
w3lzx is offline  
Reply With Quote
Old 08-05-2005, 05:06 PM
  #2  
Senior Member
True Car Nut
 
95naSTA's Avatar
 
Join Date: Feb 2003
Location: Philly
Posts: 4,508
Thanks: 0
Thanked 0 Times in 0 Posts
95naSTA is on a distinguished road
Default

1. Yep there is a high and low setting for the fans. both should come on with the a/c.
2. Nope. Nothing has to be tuned. The 180 will work no problem.
95naSTA is offline  
Reply With Quote
Old 08-05-2005, 05:11 PM
  #3  
DINOSAURUS BOOSTUS

Expert Gearhead
 
BillBoost37's Avatar
 
Join Date: Mar 2005
Location: Enfield, CT
Posts: 41,391
Thanks: 0
Thanked 0 Times in 0 Posts
BillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of light
Default

On the fans, both fans should come on at both speeds. The only thing that changes is the speed they operate at. Once the A/C is requested both fans should come on at high speed.

Each fan has a seperate connector and I believe a seperate resistor as well. (two resistors on the driver side fan) If my hunch is right it'* one resistor per fan.

Another thing to keep in mind is low speed fans turn on at 215 degrees, and high speed fans turn on at 225 degrees or when A/C is requested.
BillBoost37 is offline  
Reply With Quote
Old 08-05-2005, 05:14 PM
  #4  
Senior Member
True Car Nut
 
Join Date: Jun 2003
Location: Purgatory
Posts: 6,313
Thanks: 0
Thanked 0 Times in 0 Posts
PontiacDad is on a distinguished road
Default

1. Both fans should run with the a/c on. They are connected in series for slow speed and parallel for fast speed.

2. The stock pcm will not turn on the fans untill the temps reach 195*f, if you put in a 180 tstat there is a chance the car will be cool enough not to run the fans. There is a fix around this that you can get from zzperformance. its called an 'e stat' and it work real well, I use it with my 160* tstat and have had no troubles with it.
PontiacDad is offline  
Reply With Quote
Old 08-05-2005, 07:12 PM
  #5  
DINOSAURUS BOOSTUS

Expert Gearhead
 
BillBoost37's Avatar
 
Join Date: Mar 2005
Location: Enfield, CT
Posts: 41,391
Thanks: 0
Thanked 0 Times in 0 Posts
BillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of light
Default

PDad...we were both off a little. Trying to supply the best info. so out comes the book.

From the 97 FSM
While in low speed operation the circuit supplies the right side cooling fan motor, the left side cooling fan motor is supplied a feed through a resistor causing it to run at low speed. When high speed operation is commanded the right side fan continues to run at low speed, but circuit B supplies a feed directly to the left side cooling fan motor causing it to run at high speed.

PCM commands low speed fans operation when the following conditions are met:
- Vehicle speed is less than 58 mph
- Engine coolant temperature is above 100 C / 212 F
OR
- Vehicle speed is less than 40 mph
- Intake air temp is above 9 C / 48 F
- A/C refrigerant pressure is greater than 190 psi

High speed is commanded when the following conditions are met:
- Vehicle speed is less than 65 mph
- Engine coolant is above 108 C / 226 F
OR
- Vehicle speed is less than 50 mph
- A/C refrigerant pressure is above 260 psi

So basically from the book even if you are over 226 F your fans shut off once you reach 65 mph. Which makes sense because at that point you are most likely getting more airflow from speed then the fans can deliver.
BillBoost37 is offline  
Reply With Quote
Old 08-06-2005, 08:18 AM
  #6  
Senior Member
True Car Nut
 
Join Date: Oct 2002
Location: Groton, CT _NEBF 05, 06, 07_
Posts: 2,703
Thanks: 0
Thanked 0 Times in 0 Posts
markwb is on a distinguished road
Default

The 2000+ Bonnevilles utilize the series/parallel lash up via relays to operate the cooling fans in slow/fast respectively. Not sure about the 96-99'*, but I think you're right on the money with the resisters being inserted for slow speed ops, Bill.
markwb is offline  
Reply With Quote
Old 08-08-2005, 03:11 PM
  #7  
Junior Member
Thread Starter
 
Join Date: Aug 2005
Location: Waldorf, MD
Posts: 3
Thanks: 0
Thanked 0 Times in 0 Posts
w3lzx is on a distinguished road
Default

Thanks guys for the information !!
Should be no problem to fix now.

Bob
w3lzx is offline  
Reply With Quote
 
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
jmark
Everything Electrical & Electronic
14
01-02-2007 09:10 PM
RogerH
1992-1999
46
08-19-2006 04:59 PM
jlathem
Performance, Brainstorming & Tuning
14
09-28-2004 01:08 AM
CraZyDriVer868
1992-1999
2
06-19-2003 09:37 AM
Bret1994SSEI
1992-1999
1
06-16-2003 08:49 PM


Thread Tools
Search this Thread
Quick Reply: Radiator fan(s) / Thermostat Questions


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.