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Don't really know the history except for the 13 years I've owned it.
Now ya got me wondering if I would be wasting my time by pulling it apart.????????
Only one way to know for sure I guess......
Maybe more than one way to see... I got a $15 USB borescope camera from ebay and have been looking around inside mine. USB goes to a laptop and that is the monitor and video recorder. The unit works well. Has a camera and 4 LEDs on the end 10mm diameter. 5 meter length waterproof not needed for this but lot of length to work with. Harbor Freight also sells one.
On mine there was a milk cap I was able to get out in there. Old Borden Cow face on it. There is a 3/8 socket short extension on the bottom of the case and some small zip ties someone probably also dropped in there. I'm going to visualize all the vacuum actuators to see for sure how they work as I work the controls for them. Haven't got much time to work with it yet.
I'm working to make mine blow harder up top too. In mine the servo that controls A/C or heat was weak not shutting off the heat side altogether. There should be little or no cool air coming out the passenger side trans tunnel, that is where heat should come out and should be closed off with A/C. And if it leaks there the flow is less to the top vents.
The servo can be reached taking the driver side tunnel cover off and reaching to the very front by the driver's toe position. I'm going to inspect the action of the door with my borescope to see what it is doing before taking it apart and changing any parts. I should be able to see that door with the scope put in the heater vent on the passenger side.
Found something that fixed the weak blower out the top and the ball vents.
77 here. In the engine compartment there is a white yellowish vacuum line that is supposed to go to the heater hose shut off valve when the system is put on A/C to stop hot water from going into the system. Many times that line is broken. Mine was. If it is open to air when you go to A/C instead of vacuum to the heater shut off it just is a nice vacuum leak making all the other actuators get much less vacuum and not being able to do what they are supposed to do.
I plugged that white yellowish line and now everything works much better, blows strong from the right vents.
That vac line comes out from the firewall right behind the distributor.
Found something that fixed the weak blower out the top and the ball vents.
77 here. In the engine compartment there is a white yellowish vacuum line that is supposed to go to the heater hose shut off valve when the system is put on A/C to stop hot water from going into the system. Many times that line is broken. Mine was. If it is open to air when you go to A/C instead of vacuum to the heater shut off it just is a nice vacuum leak making all the other actuators get much less vacuum and not being able to do what they are supposed to do.
I plugged that white yellowish line and now everything works much better, blows strong from the right vents.
That vac line comes out from the firewall right behind the distributor.
Awesome!
I'll chech that this morning!
Still gotta down a couple cups of coffee, then I'm headed out to the garage to tackle the evaporator - but I'll check that first.
To me it looks like you may be ok in there. The screen did what it was supposed to and stopped the large debris. Look at the pic above, clogged with leaves and big things that your screen would not have let in. Do you have history on how it was cared for? Stored outside?
OMG - so the fresh air travels down both sides thru these?? Wow - can you snake a small vacuum hose down these to clean it out - I have a very small hose attachment I use on the wife's dryer to suck out the lint out inside it.
OMG - so the fresh air travels down both sides thru these?? Wow - can you snake a small vacuum hose down these to clean it out - I have a very small hose attachment I use on the wife's dryer to suck out the lint out inside it.
I believe it only comes in through the passenger side where the blower motor is, and to do ANY vacuuming, the blower motor HAS to come out first.
Well, that was a ton of work only to find out my evaporator was pretty darn clean
So it's all back together again but no better than it was.
Tomorrow morning I'm going to pull the passenger side dash and inspect the ac doors.
Did plugging the vac line to the heater valve in the engine compartment help with the force of air coming out the top? If it is connected to your heat valve it still might be worth pulling off and blocking because the valve may be letting the line leak.
Post pics of your heater box interior if you took them.
What about everywhere else? Is the floor the only area not receiving air? If that's the case, it changes everything, and I'd lean towards either a vacuum door not receiving a vacuum signal or the diaphragm for the door in question is leaking to the point it cant open. Or a stuck door. Mine is a 74. The AC control in the console has a handful of vacuum lines, and it's that pod that sends the vacuum signal to each blend air door, be it defrost, floor, dash or bi-level. With a Mighty Vac you can test and prove each diaphragm for proper operation. I just wish it wasn't such a pain in the keester to access a lot of this stuff. Like a small kit car with a lot of crap jammed into a very small area. If I didn't know better, I'd say Mitsubishi designed the C3. They are great at jamming square pegs in round holes! This said at the end of the day I love my C3. Be glad when I'm driving and not working and spending money
While the engine bay is open before the new motor is installed, I decided there wasn't a better opportunity to get the blower motor swapped out. I went through the whole rig-a-moro of opening the perfectly sealed airbox to find nothing but a few leaves. Now I have to re-seal something that didn't require opening!
I suggest the following procedure to replace the blower motor:
1. Evacuate the A/C coolant, so you can break the connection and move the lines out of the way.
2. Remove the radiator overflow reservoir tank - there are 3 screws inside the right front wheel well.
3. Remove the power and ground lead from the old motor.There are 2 separate wires.
4. Remove the 5 hex head screws and pull out the old motor.
5. Go to NAPA and purchase a dual lead connector pigtail to mate with new motor. The blade connector on the left is the hot lead, the right blade is ground.
6. Install the C4 blower and 3/4" spacer that you made. (I went to a hardware store and bought five 1.5" #8 self tapping phillips head screws as they were much easier to tighten with screwdriver.
7. Connect the vent tube to the motor from the airbox.
8. Cut the old single connector and splice the hot lead to the pig tail, use shrink tube to insure weatherproof.
9. Splice the ground lead to a 10 Gauge wire and and connect the other end to good ground on the block. (This will allow maximum current flow to the blower).
10. Apply A/C "perma gum" tape then aluminum tape over the top to seal the spacer, motor and screws to the plenum and prevent moisture intrusion.
11. Re-install reservoir
12. Re-connect A/C line, check for leaks and add refrigerant.
Last edited by JagNorb; 08-01-2014 at 06:21 PM.
Reason: edit
So to recap some of this thread for future searchers in need of strong air flow:
1. Check if there is a change in where air comes out the vents as controls are changed.
2. Check to see if the vac tube to the heater hose shut off valve in the engine compartment is connected.
3. Check to see if you feel any air at the passenger side trans tunnel, with A/C there should not be air coming out there. Switch to heat and max flow should come out of there.
4. Check the status of the fan, has it been upgraded with a larger ground?
5. Check to see if there is debris in the air box
6. May still not like the output of the C3 fan when given full power.
7. Be sure engine is running when checking the system
8. Check to see that the multi level fan switch works. Fan is on low all the time. On Max A/C fan is on highest. On normal A/C the fan speed switch should be able to change to all the set levels.
1. If there is no change with the levers moved it may be a problem with the vac valve attached to the lever that controls the vacuum system that opens the correct doors to divert air flow. An inexpensive part to replace and easy to get to.
2. The vac tube in the engine compartment is there to shut off the heater hose flow when A/C is on. If it is broken it opens up a vacuum leak and does not allow the system to divert max air to the top and side vents. Be sure that is sealed if broken or connected to the actuator.
3. This is an indication of the air solenoid that diverts air from heat to A/C maybe not working or not closing all the way. It is far toward the front of the trans tunnel by your toe when driving. Check if the vac system is working to give it vac before considering that not working and needing a change
4. The fan these cars use is meant to get ground from the METAL body of other GM cars. Fan bolted to metal for huge ground to whole assembly and one + wire running to it for power. On these fiberglass cars the ground is made by one wire coming off the fan and this wire is smaller gauge than the wire going in to the fan. Making this wire larger allows more amperage to go to the fan and will make it blow harder. Run a second ground wire to the fan.
5, There may be debris in the air box blocking flow of the fan. May need to see if there is anything blocking flow. Could check by removing the fan. May need to open the air box to get a look inside.
6. Can change to a C4 fan. This is not difficult and there are write-ups here to do it.
7. Might be obvious but you can run the blower with the key in and engine not on but the door positions to divert air where it should go runs on vacuum from the engine. Also due to vacuum when you change the lever position there is a delay as the vac builds and works the solenoid.
8. May need to change that switch or at least take it out and test and clean if needed
While the engine bay is open before the new motor is installed, I decided there wasn't a better opportunity to get the blower motor swapped out. I went through the whole rig-a-moro of opening the perfectly sealed airbox to find nothing but a few leaves. Now I have to re-seal something that didn't require opening!
I suggest the following procedure to replace the blower motor:
1. Evacuate the A/C coolant, so you can break the connection and move the lines out of the way.
2. Remove the radiator overflow reservoir tank - there are 3 screws inside the right front wheel well.
3. Remove the power and ground lead from the old motor.There are 2 separate wires.
4. Remove the 5 hex head screws and pull out the old motor.
5. Go to NAPA and purchase a dual lead connector pigtail to mate with new motor. The blade connector on the left is the hot lead, the right blade is ground.
6. Install the C4 blower and 3/4" spacer that you made. (I went to a hardware store and bought five 1.5" #8 self tapping phillips head screws as they were much easier to tighten with screwdriver.
7. Connect the vent tube to the motor from the airbox.
8. Cut the old single connector and splice the hot lead to the pig tail, use shrink tube to insure weatherproof.
9. Splice the ground lead to a 10 Gauge wire and and connect the other end to good ground on the block. (This will allow maximum current flow to the blower).
10. Apply A/C "perma gum" tape then aluminum tape over the top to seal the spacer, motor and screws to the plenum and prevent moisture intrusion.
11. Re-install reservoir
12. Re-connect A/C line, check for leaks and add refrigerant.
Great write up with pics.
On mine instead of the aluminum tape I cut gaskets from gasket material for each side of the fan adapter to seal possible air leaks, shot the adapter with a little black spray paint and it seals and is really not visible unless you look for it.
40 years of crap, .... no way to stop without a time machine ! you could have fabbed a screen for the air intake area 40 years ago.
Interesting you brought that up. My 74 has screens in both sides. I thought it was factory. One way or another, it's these screens (passenger side especially) I attribute to having VERY little substance in the housing when I removed for cleaning. I remember cussing about all the factory Missouri slop bucket tar I had to remove around every crack and crevice of the firewall, only to be a little pleased there was screen in spite of the sloppy tar job around it. I lef tit and the tar surrounding it alone, only coating it with paint
Hi all, what all does it take to get to the evaporator? I'm not sure I saw it in the thread anywhere or I more than likely missed it;
I'm would like to try to see if there is debris blocking mine and causing a weak ac flow. I currently have my valve covers off which seems to provide easier access to the evaporator housing;
I'm just trying to find out all that's involving with removing it;
Consider spending $10 to $25 on a USB borescope on eBay. Can snake that in places to inspect things that would take hours and money to get to sometimes just to find no problem. Or to find a problem worth what it takes to open it up and fix it.
Search "Borescope" on eBay to find something of your cell phone or computer.
07-16-2014, 09:57 PM
