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trathson
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Feb 15, 2014, 1:50 PM
Post #1 of 18
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91 Civic, overheating
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I have a 91 Honda civic thats overheating. The first time, it was sitting in a line, and the temp gauge went into the red and it started to steam. It was turned off and checked for leaking, and a lack of oil or coolant.
The coolant wasn't completely full, so it was topped off. The second time, the temp gauge did not go into the red, but the coolant overflowed into the overflow tank and start bubbling/boiling out (not sure which).
The radiator fan was not running in either case. So, my questions are whether the coolant thermostat controls the radiator fan, or whether the fan has its own coil.
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Tom Greenleaf
Ultimate Carjunky
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Feb 15, 2014, 2:03 PM
Post #2 of 18
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Re: 91 Civic, overheating
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Quote ">>So, my questions are whether the coolant thermostat controls the radiator fan, or whether the fan has its own coil.<<"
The thermostat for coolant flow is not the one that makes fan(s) come on.
It overheated for sure if you saw the steam and gauge in the red is enough proof for me. It's probably not properly full at all if you only filled at the recovery tank and now the possibility of a head, head gasket blown and still need to know why fan(s) didn't come on and fix that,
T
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trathson
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Feb 15, 2014, 3:33 PM
Post #3 of 18
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Re: 91 Civic, overheating
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Ok, I disconnected one of the radiator fans, and hooked it to the battery. It did not run. I can't really get to the lead on the other though, but the odds of both fans going bad at once... I wouldn't think would be that low.
(This post was edited by trathson on Feb 15, 2014, 5:05 PM)
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Tom Greenleaf
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Feb 15, 2014, 3:48 PM
Post #4 of 18
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Re: 91 Civic, overheating
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I have no clue how you tried to force one to work. It would need power and ground. Careful and use fused jumper wire doing stuff like that. IDK the exact intention for twin fans. One could be just A/C or only run both if hot enough to need both.
#1 check is with the keys out and with a small stick will the blades of the fans turn at all? One could have been dead for a long time and just now the other or a common power source for both?
The more important and up front issue is that it overheated and you really don't know if it's filled up properly or not yet IMO. You said you just topped it off and don't know how or where you added coolant so it's probably still low and nothing is going to work right till you at least know that then right away suspect a head gasket blown - doesn't take much and they are toast AND can be adding combustion gasses to system making it bubble/barf out to recovery tank a little or a lot or other ways they can fail also.
It's an old car now so begin with just knowing it's full of coolant and can stay steady with temp. You really don't need fans much if driving over 30-40 MPH on most except for A/C I think for the year fan for the condenser would run all the time when A/C is requested or many using defroster,
T
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Hammer Time
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Feb 15, 2014, 4:30 PM
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Re: 91 Civic, overheating
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Do you have a 1.5 or 1.6 engine?
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trathson
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Feb 15, 2014, 5:16 PM
Post #6 of 18
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Re: 91 Civic, overheating
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Its a 1.5 litre.
The fans are run in series, so they both share the same power source. I tested the fan by hooking alligator clips to its plug leads, and hooking them to the battery.
The fan blade on the driver side has disconnected from its shaft now that I look at it. That said, I didn't hear the shaft spinning when I tested it.
The fan blade on the passenger side spins freely.
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Hammer Time
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Feb 15, 2014, 7:25 PM
Post #7 of 18
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Re: 91 Civic, overheating
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Does this car have AC?
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trathson
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Feb 15, 2014, 10:30 PM
Post #8 of 18
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Re: 91 Civic, overheating
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Yes 
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Tom Greenleaf
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Feb 16, 2014, 12:25 AM
Post #9 of 18
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Re: 91 Civic, overheating
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HT will be back with info on this car w A/C how it should be wired. Let's look at what you said in the first post and get this going.........
Quote">>I have a 91 Honda civic thats overheating. The first time, it was sitting in a line, and the temp gauge went into the red and it started to steam. It was turned off and checked for leaking, and a lack of oil or coolant.
The coolant wasn't completely full, so it was topped off. The second time, the temp gauge did not go into the red, but the coolant overflowed into the overflow tank and start bubbling/boiling out (not sure which).<<"
OK: It hasn't been warm enough need A/C for most places so that fan wouldn't have been working and not so sure that one alone would cool the radiator much? I'd have to look right at the layout with this dual fan deal just to see how much of the radiator each could cool. Doesn't totally matter yet as you found one broken which is the cause of the overheat no doubt when caught up in stop and go slow traffic even if cool or cold out fan would come on and didn't so overheated.
Again, you said "topped it off" and that isn't enough yet for just that part of the problem. To know this is full again IS NOT JUST THE RECOVERY TANK it has to be filled at the radiator itself, thermostat when running again later will open and burp out some air and coolant level would drop in view if you have a radiator cap but at first could bubble out to recovery tank which could be pressured and the only fill spot for this car not enough alone yet.
If heater works well and full blast there should be an adequate amount of coolant in the system to begin self purging out air in the cycles of cold to warmed up not always fast enough so it remains unknown.
UNPLUG AND LEAVE THE BROKEN FAN MOTOR INOPERATIVE AS IT CAN ONLY HARM THINGS NOW IF NOT ALREADY. That's the cause IMO as said but the fix is going to be unknown for a while as this may have wrecked the engine's head and or head gasket, still need the fans, relays involved or wiring that could have burned out now knowing one fan motor is physically broken.
Stinks but the total fix could exceed what this car is worth! My point is to know it's full first and doesn't need a head or head gasket job as you could cool the radiator with a garden hose without the fans for now if available to you.
New parts may be trouble to find in time and used is always a guess if things are good.
I can't know but how much $$ are you willing to put into this car? My point is find out as best you can how much possible damage may have occurred beyond the fans so you can decide how to proceed COST wise with the least waste,
T
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Hammer Time
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Feb 16, 2014, 5:43 AM
Post #10 of 18
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Re: 91 Civic, overheating
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OK, these fans are not wired in series. They don't even serve the same function although they may run simultaneously at times. One fan is a cooling fan and one fan is a condenser fan. They are wired individually and don't even share the same fuse. Two fans that were wired in seris would run at half speed.
There is a temperature switch on the driver's side of the engine, near the timing cover. This switch closed to ground the wire for the cooling fan relay. The cooling fan should be receiving power all the time with the key on and the control side will be the motor ground.
The condenser fan will only receive power when the compressor is powered.
There are 3 different wiring diagrams that vary slightly depending on whether they are American or Canadian vehicles.
Here are the 2 American versions
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trathson
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Feb 16, 2014, 11:20 AM
Post #11 of 18
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Re: 91 Civic, overheating
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Ok, I ran the A/C and neither fan came on. The radiator is still full of coolant after running the car, and no leakage can be seen where it has been parked.
To look for a cracked head, I would be looking for coolant and oil mixing yes? A blown head gasket, I would be looking for steam coming from the engine or tailpipe correct?
There is no steam coming from the engine block itself, just what seems to be residual coolant evaporating from where the overflow tank went over. I put my hand in front of the muffler for 30 seconds or so, and it did come away damp, but it didn't smell like coolant. Its color was not discernible.
So, if I read what you guys are saying correctly, I need to replace the broken fan, and check the wiring, relays, and fuses leading to each?
(This post was edited by trathson on Feb 16, 2014, 11:25 AM)
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Hammer Time
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Feb 16, 2014, 11:29 AM
Post #12 of 18
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Re: 91 Civic, overheating
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You need to diagnose the problem with the fan correctly. Don't look for anything else until you get the fans working the way they are designed to. Check the pertinent fuses first. Locate the fan switch with the single black wire and try grounding that wire to see if the rest of the circuit works.
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trathson
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Feb 17, 2014, 12:29 PM
Post #13 of 18
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Re: 91 Civic, overheating
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Ok, I'm at removing the physically broken fan. Its wedged between A/C lines and the radiator. I really would prefer not to remove the radiator to get the fan out, but out of your guys experience, is that necessary?
(This post was edited by trathson on Feb 17, 2014, 12:30 PM)
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Hammer Time
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Feb 17, 2014, 12:59 PM
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Re: 91 Civic, overheating
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You shouldn't have to remove the radiator.
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trathson
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Feb 17, 2014, 5:28 PM
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Re: 91 Civic, overheating
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Ok, I took both fans out. Neither of which run when hooked to a 12 volt battery. One might have been broken for a while, but both being bad at once seems a bit odd.
I tested the plugins for both fans, the driver side(physically broken one) did not have power, but did previous to me removing the fan. So I'm trying to figure what happened there. The passenger side power.
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Hammer Time
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Feb 17, 2014, 5:36 PM
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Re: 91 Civic, overheating
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I'm not sure what you are trying to say here. If you have broken or non-working fans, then replace them with working fans. Don't worry about the rest of the circuit until you have known working fan motors.
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trathson
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Mar 5, 2014, 6:05 PM
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Re: 91 Civic, overheating
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Just wanted to update this.
I replaced both fans. The radiator fan I bought new, and the condenser fan I got from a local junk yard (which I tested to be sure it ran).
So, I install both fans, and the car is working fine. That said, the condenser fan is not running when I turn the AC on. Granted, its 30 degrees outside, but with any AC unit I've come across, the condenser fan runs constantly. So, do cars have a temperature switch for the condenser fan?
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Hammer Time
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Mar 5, 2014, 6:12 PM
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Re: 91 Civic, overheating
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You can't test anything in an AC system in those temps. The condenser fan likely operates off a pressure switch and the temp will definitely effect the pressure.
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