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Cooling fans, oh boy

2K views 27 replies 5 participants last post by  ekvh 
#1 ·
On to the next problem. 93 STS N* I have zero cooling fans in all situations. Preliminary checks showed a blown 50 amp fuse. Thought I was lucky,-----not so much. I will be checking relays and associated wiring tonight. Any tips from the wise. I read that the relays were under the fuse compartment on the driver's side engine compartment, but they are not. The only other codes I have are AO47, I think, and an AO 48 and 49 history. I cannot seem to get the AC to kick on to add refrigerant. I have tried clearing codes, but no luck. Being the fuse was blown and the fan is supposed to come on with the AC, maybe they are related. Thanks in advance for any suggestions, Eric

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I haven't tried, because I didn't know, the PS08 on the override function. Does that try to turn the fans on?
 
#2 ·
On to the next problem. 93 STS N* I have zero cooling fans in all situations. Preliminary checks showed a blown 50 amp fuse. Thought I was lucky,-----not so much. I will be checking relays and associated wiring tonight. Any tips from the wise. I read that the relays were under the fuse compartment on the driver's side engine compartment, but they are not. The only other codes I have are AO47, I think, and an AO 48 and 49 history. I cannot seem to get the AC to kick on to add refrigerant. I have tried clearing codes, but no luck. Being the fuse was blown and the fan is supposed to come on with the AC, maybe they are related. Thanks in advance for any suggestions, Eric

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I haven't tried, because I didn't know, the PS08 on the override function. Does that try to turn the fans on?
======================
codes are meaningless without their definitions -
 
#6 ·
I have cleared codes numerous times to no avail. I tossed in a new fuse and used the PS08 override to turn on the fans. They worked. Then they didn't. 50 amp fuse toast. I went and got a 50 amp breaker and wired it in to investigate. With both fans on, it quickly created smoke at the breaker. I poked a little and decided to disable the passenger side fan since it was easily accessible. With it disconnected, the driver side fan ran no problem. So I removed the passenger fan. It is not free spinning and feels rough turning. I stuck an ohm meter on it and it showed a little resistance between the two terminals. When I turned the fan blade manually the ohms fluctuated. My guess is the fan is toast. I am surfing for a new one now, but would feel better if someone could confirm that the fan circuits should not show any continuity between the two terminals.

On a different note, the previous owner informed me the AC never worked for 12 years. I will have to read up on AC as it appears to likely be more than just low.

Thanks again in advance for any comments.
 
#8 ·
low refrigerant WILL disable the compressor -
and with a disabled compressor -
the electric cooling fans will NOT be triggered -

your AC system could be low -
or you could have a defective pressure switch -

Wow, disable fans from low coolant? Surely the temp at 228 would kick in and override the fans. If not, no wonder so many overheating issues with this car/engine.

As to my static pressure, excuse my ignorance, if that means the non running pressure, it was very low. I don't have proper gauges and assumed it was just needing a bit of refrigerant. I was able to add, and the pump was running for a while, but when I thought I had enough in, I got back in the car and the temp was 247 and rising. It was dark and raining, and I decided to go for a quick ride to cool it down since the fans weren't on. It cooled down quickly, but as I rode I got the AC system was overheated. I probably wont get back to this until Sunday night.

Can anyone confirm the fan resistance? Being it's a plastic housing, I assume the two wires are a positive and a negative and shouldn't show any resistance between them, one feeding the armature and the other the field?
 
#9 ·
As to my static pressure, excuse my ignorance, if that means the non running pressure, it was very low. I don't have proper gauges and assumed it was just needing a bit of refrigerant. I was able to add, and the pump was running for a while, but when I thought I had enough in, I got back in the car and the temp was 247 and rising. It was dark and raining, and I decided to go for a quick ride to cool it down since the fans weren't on. It cooled down quickly, but as I rode I got the AC system was overheated.
Either I am misunderstanding you, or you are misunderstanding the system.

You are correct in that static pressure means with the system not running. Static pressure is generally around 70 psi, but is never used to check refrigerant levels (or anything else for that matter).

You MUST have the compressor operating to draw in refrigerant when you are recharging the system. It CANNOT be done in the static mode (unless the system has less pressure than the can obviously, then it will take "some" refrigerant).

You CANNOT "guess" at when you "have enough in". You need a real set of gauges, (not the low pressure gauge only that comes on the refrigerant cans).

Refrigerant has NOTHING to do with engine temperature. Refrigerant is in the A/C system. The A/C system keeps YOU cool, coolant aka anti-freeze cools the motor and keeps IT cool.

A/C systems DO NOT overheat. They simply loose cooling ability. Engines DO overheat.

The radiator fans should come on when the ECT reaches 224 deg. F or anytime the A/C system is operating.
 
#11 ·
Im doing the best I can, (I have limited RAM) but I thought when I drove it to cool it down, that it said ac overheated, but perhaps it said coolant system. I haven't had a chance to check it again. I guess I will hook the fan with the resistance issues and see if it cooks the wires quickly and from there replace it or start chasing wires for a short. Car is a 93.

I will address the fan issue before the AC. Once the fans are operating I will try to get the AC clutch to engage and check refrigerant properly. I have a cousin nearby with gauges.
 
#12 ·
==================================
I thought when I drove it to cool it down,
that it said ac overheated,
but perhaps it said coolant system.


this - copied from page 137 the Owners Manual -

A/C OVERHEATED - A/C COMPRESSOR OFF
If the refrigerant system ever reaches an over-pressure condition, this
message will appear to tell you that the air conditioning compressor has
been turned off. Air conditioneadi r will not be deliveredt o cool your
vehicle. If the pressure returns to a normal operating rangey, ou must
select “AUTO”, “DEFOG” , or Defrost to start the compressor. If this
message continues to appear, have the system repaired as soon as
possible to avoid compressor damage.


-------------------------------------

or this - from page 139 -

ENGINE HOT - A/C COMPRESSOR OFF
This message will appear when the Climate Control is in “Auto” or
Defrost and the engine coolant is hotter than the normal operating
temperature. To avoid added strain on a hot engine the air conditioning
compressor is automatically turned off. When that happens, air
conditioned air is not delivered. If the coolant temperature returns to
normal, you must select “AUTO”, “DEFOG” or Defrost to return to a
normal A/C compressor operation.

-----------------------------------

you might be over-thinking this whole fan deal -
just replace the fan - and be done with it -

then move on to the AC system -

--------------------
oh -
you should read the Owners Manual -
LOTS of valuable information in it -

if you don't have the OM -
go here for a free download -
http://justgivemethedamnmanual.com/cadillac/cadillac-seville-owners-manuals/
 
#15 ·
Motor coming Thursday, I hope. New problem: hole in radiator. Silver lining: showed me a leak in the front tire, lol. I hope this doesn't indicate a head gasket. Has anyone done a plastic repair of the radiator ends on their own? I might start a new thread. I was looking closely at my heater/ac fan enclosure, the one on the firewall, and the plastic on that has degraded and is becoming crumbly.
 
#16 ·
Keep in mind that the radiator side tanks are 11 years old and have been subjected to many, many heat/cool cycles. Rather than repair the side tank, you might consider replacing them. That said, I have heard that replacing the radiator is not much more expensive (not to mention, easier).
 
#17 ·
Good advice, Ranger, I may try a temporary fix tonight and make sure I don't have a head gasket out, but a new radiator can be had for $70, so that is what I will do. Looks fairly easy to replace too. I'm thinking it will be prudent to make sure it's not the result of a head gasket failure. Is there a track record of how they are revealed? Do they fill the radiator with pressure or do they steam it out through the exhaust? Both? At this point I don't have the steam out of the exhaust. I'll give the radiator the smell test tonight, but my nose has seen better sniffing days.
 
#18 ·
Normally, a Northstar with failing head gasket(s) will begin a slight cold start miss (coolant in a combustion chamber) that disappears in a few seconds............ not enough to show any more than a cool morning's cold start tailpipe vapor for a while. Then, as failure progresses, some coolant loss from greater leakage into a cylinder. Then, sudden overheats accompanied by radical coolant blowoff due to both exhaust gas pressure in the cooling system and overheating combined - loss of coolant = no coolant pumping = overheat. The exhaust gas itself does NOT overheat the engine - loss of coolant does. In rare cases, a radiator end tank may crack, but that's few and far between because the 16 or 18 psi surge tank cap vents off any overpressure.

If a radiator end tank cracks or a hose blows its due to age or deterioration - not head gaskets.

Northstars with failing head gasket(s) do not normally put water in the oil or vice versa.

Use this to sample the air over the coolant in the surge tank after at least a 15 minute drive. Follow the instructions and don't try to "make it better" by testing for any longer than instructed.

http://www.sjdiscounttools.com/lis75500.html
 
#19 ·
Slight cold start miss, huh disappears in a few seconds? That sounds familiar. I found a bad plug wire and swapped it today and it sounds better, but I am leery that something is amiss. It has 50k since a gm rebuild, 125K on the car, but the gm rebuild was due to the gm dealers mistake on a different issue. The guy who bought it and sold it to me recalls them saying they, the dealer, screwed this up somehow and had to rebuild it in order to sell it. I am hoping it was done by the book, but being that they were taking the beating on it, I fear it may have been hastily done. Fingers crossed.
 
#21 ·
The wires are correct. Thanks Sub.409. I decided to just get a new radiator. Looked at the work involved with the transmission lines and thought I want to be done when I'm done. Hope it gets here before the cold weather sets in. I am a sucker for these older cars, but I've found that if you dump a little money in up front you can get 5-6 years of decent running out of them. I'm hoping this is the same. I bought it for $600, now at about $900 and probably will need another $5-600 to get it to where it should be, but it is clean and modest miles, 125K.
 
#22 ·
Swapped the rest of my plug wires, got rid of the miss at cruising speed. Poked around the DTC some and erased my AO47 code and it hasn't returned. Right now I have no codes, but I can't tell if I'm getting AC as it's only 34 degrees here, but it doesn't show low refrigerant or compressor turned off. Am I going to be that lucky? I won't get my radiator until next week probably. It's coming Fedex from Cali. I have to leave Thursday for the weekend.
 
#24 ·
Thanks, Ranger, I will try that. When I visually look to see that the compressor clutch is engaging, will I see the most outside plate turning along with the belt? Most compressors I have watched, you can. If I use the PO20 check in the Data Outputs I should see it engaging every four seconds also? Or I have a bad relay? I think that's what the manual says. I haven't gotten my volume2 yet.
 
#27 · (Edited)
Tried more last night, refrigerant is low. At least I know how to by-pass to engage the clutch when I do fill it. I may wait until next spring to do it. I pulled the radiator last night. That was surprisingly easy. Radiator is supposed to be here Monday, probably a sure sign of snow.
 
#28 ·
Radiator in, fairly easy, however you do have to put the oil lines in more than finger tight, lol. I am afraid I have a head gasket possibly going as first starts are a bit rough, but after that it runs great. I have turn signal issues and other electrical items to chase before it gets cold. No codes accept refrigerant low. I'll probably need the system checked by a pro. Thanks for the help. I'll be back, I'm sure.
 
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