E-fan install 1991 Suburban

Discussion in 'GM Electrical Tech' started by Crawdaddy, Mar 19, 2013.

  1. Crawdaddy

    Crawdaddy Moderator

    Well, those of you that have been around GMTC for a while know that I can't keep my tools off my Suburban, and this is no different. I am working on installing an electric fan on my 1991 Chevy Suburban. Why am I doing this? The answer is that the mechanical fan takes up a lot of space and isn't the most efficient at moving air, particularly while idling. It's hot down here, so air not moving over the a/c coils means it's not as cold as it can be, though to be honest the a/c worked pretty well before. The fan of choice for this project is the Lincoln Mark VIII fan. Why the Mark VIII fan? Well, it's fabled as the fan that moves the most air out on the market; claimed CFM is 4000+ but noone can agree exactly how much. Another excellent choice of fan are from Ford Tauruses, and while I have a couple of those fans, the CFM is supposedly not as much, though still high. I scored the fans for just under $20 each. So, let's get installin'!

    So, here's what I'm starting with, a boring 20-year old mechanical fan and insanely huge shroud:

    [​IMG]

    So, let's try to modernize it some. I took off the upper shroud and there's already a good bit of space freed up:

    [​IMG]

    Here I've completely removed the fan and shroud. It's so cavernous, I think I can hide in there with the engine. You can also see my triple hose clamp job for my transmission cooler lines:

    [​IMG]

    Next, I plopped the new fan in the engine compartment to try to get a feel of where I wanted to put it. About center looked good and seemed to cover most of the radiator. I'd say I have 80% coverage by the shroud:

    [​IMG]

    [​IMG]

    Looking at what I had to work with, I decided that I could reuse the mounting points for the lower fan shroud to mount the bottom of the fan and I'd fab up new mounts for the top. So, I took some aluminum flat bar and bent up a couple of 90-degree tabs:

    [​IMG]

    I then put the fan back in the hole, made a couple of measurements, and mounted the tabs to the bottom of the fan:

    [​IMG]

    I cut off the original factory mounting tabs with a hacksaw since they would not be used to clean up the sides:

    [​IMG]

    I took some measurements for the top mounts, sketched them up, and bent up a bracket that I would later duplicate for the other side:

    [​IMG]

    And then installed the fan for the last time:

    [​IMG]




    So, all the mechanical install is done. Now, I need to decide what I'm doing for the fan control. It is a 2-speed fan, and I can decide to operate it just in one speed, or step it between the 2, but either way, I need to find a fan controller. The alternative is to try to roll my own fan control setup with a temp switch and a constant-duty relay. Any suggestions on what I should do for the electrical?
    Last edited: Mar 19, 2013
  2. Pikey

    Pikey Moderator

    Nice work! You made it look easy. I have seen some other installs that make it look like a pain.
  3. Crawdaddy

    Crawdaddy Moderator

    That was about 5 hours of work that I spread over 2 weekends. The brackets aren't perfect and pretty because I bent them in a vise with a crescent wrench and hammer, and overall it's not show quality, but nothing on the truck is. I'm happy so long as it works.

    I am considering rolling my own fan controller with a fixed temp switch and a constant-duty relay. However, I'm still up in the air where I'd put the temp switch. Right at the thermostat housing seems to make sense, but I haven't found a water neck with a sender port that will fit the application yet. There's a pipe plug in the passenger head that's used on the drivers head for the engine temp gauge, but I don't know if that would make the fan never turn off because the temp would never get below the trip point. It might work if I used a 210 degree switch, but I'm still unsure. I am VERY much open to suggestions. Electrical is my forte, but this also entails thermo-mechanical engineering too. Collinsperformance has a similar write-up with a Taurus fan on his motorhome, but I can't find it at the moment. It used to be stickied.

    EDIT: it wasn't Tim, it was Collinsperformance. Here's a link to his thread: http://www.gmtruckclub.com/forum/showthread.php/6800-Cooling-Electric-Fan-Taruas-Fan-Install
    Last edited: Mar 19, 2013
  4. Pikey

    Pikey Moderator

  5. Crawdaddy

    Crawdaddy Moderator

    That might just be the ticket for putting a temp switch in. I am concerned that the height/angle of the outlet might put it right in line with the reinforcing bracket for the a/c compressor and belt tensioner. I'm gonna see if my friend can get one for me to check out.
  6. Pikey

    Pikey Moderator

    There are a few different types on that site. I am sure if you google it you may find the correct outlet angle.
  7. Crawdaddy

    Crawdaddy Moderator

    I talked with my friend who works at AutoZone. 814899 is another neck that might work and is cheaper. It actually has 2 ports on it and is in stock whereas the Mr. Gasket one is special order only.
  8. Crawdaddy

    Crawdaddy Moderator

    I picked up the 814899 water neck last night and it looks like it will fit, but now I'm looking for a hose to fit. I might end up using a universal hose and make a couple brackets to route it, but I'd much rather use a factory pre-formed hose. The hose for a 90 Chevy Suburban seems like it might fit, but from the pics it seems like it might go to a passenger-side radiator outlet where I need a drivers-side one. Also, the hose at the engine side has to make a sharp corner upward immediately coming off the water neck. It'll be an interesting puzzle to figure out, but I think I have it.

    I was planning on changing the hoses and thermostat while I was at it anyways since they're original to as long as I've had the truck.

    - - - Updated - - -

    So far, this controller from Derale is looking like the fan controller I will most likely be using: http://www.summitracing.com/parts/der-16749/media/images . I will also need to tie that controller to a heavier-duty constant duty relay to feed the hungry needs of the fan. Choosing the relay will take some research or a custom mount made because most heavy relays use the mounting tabs for grounding of the relay and the fan controller output goes to ground to power the fan.

    But for that price, I could get a static temperature switch like this: http://www.summitracing.com/parts/der-16731/overview/ and probably get the same result.
  9. Crawdaddy

    Crawdaddy Moderator

    Shameless bump to get more ideas. I'm still stuck on the electrical part. At this point, the plan is to get a fixed temp switch and constant duty relay to power the fan. I just can't get over $40 for a temperature switch. Does anyone know where I can get temp switches cheaper?
  10. Crawdaddy

    Crawdaddy Moderator

    Last night I ordered the Derale 16731 switch I mentioned earlier. The bill with shipping was around $35. It should be here hopefully tomorrow and if not then, Monday. Now to find a nice constant duty relay or two...
  11. Crawdaddy

    Crawdaddy Moderator

    The temp switch came in last week, though I haven't gotten to make any progress yet because I'm still waiting on relays. I ordered a couple Bosch 75 amp relays like this:
    [​IMG]

    They're supposedly rated for constant duty at 75 amps. I need 2 of them to run the fan in the 2-speed setup I intend to run, and the place where I ordered mine just happens to sell them in groups of 4 for right around $10 each. So, I'll have a spare or two to carry with me in case one goes out, but I hope that doesn't happen.

    This weekend I needed the Suburban and since I didn't have the project done, I converted it back to the mechanical fan. It took 30-45 minutes to complete and if I had to, I should be able to find the actual fan and fan clutch at any auto parts store for a reasonable price. I won't have the fan shroud, but it should be enough to get me home should the electric fan go out and I'm unable to find parts to fix it. So that's definitely a plus in my book.

    I hope to have the relays in hand this week, though the earliest I can try to get back on this project is next Sunday. Hopefully I can get this project done. In the meantime, I have what I suspect is an ignition problem to sort out.
  12. Crawdaddy

    Crawdaddy Moderator

    I was thinking today about this project and was searching for the upper radiator hose I need to get to fit the water neck I bought, when I stumbled across another solution that may be more optimal for me. I think I may use a radiator hose adapter like this: http://www.summitracing.com/parts/atm-2283/overview/
    [​IMG]

    Using an adapter like this will permit me to have more free-form placement of the temperature switch, have it electrically isolated from the block in case of shorts, and allow me to use the cheap and easy to find stock radiator hose. The adapter is pricy at around $45, but I think it would be an optimal choice for quick and easy roadside repairs where I might not be able to find esoteric parts.

    What say ya'll to my new plan?
  13. Crawdaddy

    Crawdaddy Moderator

    I have the relays in hand now, but the project got stalled due to a lack of funds and breaking a connector for the coil pickup in the distributor. I'm hoping to hit this project again hard in the next couple weeks. But not until I replace the distributor and get the truck running again.

    I have now firmly decided that I will go the adapter route and not change water necks. Having to source the proper radiator hose was proving far too hard. Any ideas what size adapter I need to put my sensor in? I need to measure the hose where I plan to put the adapter then subtract the thickness of the wall of the hose.
  14. dsfloyd

    dsfloyd New Member

    watching the thread as an efan upgrade is something I have considered doing eventually. I like the idea of the radiator hose adapter.
  15. Crawdaddy

    Crawdaddy Moderator

    The distributor has been replaced, so that issue is resolved. All I have left in terms of parts to get are the sensor adapter and wire to complete the job. I'm still a couple weeks off though because of my car needing to go to the shop for work.

    During the wait, my factory service manuals came in. I was perusing through the A/C section to try to get some info and plan out rebuilding the A/C system from scratch. While reading, I solved an issue I foresaw with my plans for the e-fan. Originally I was planning to run the fan on low normally, but when the A/C clutch was locked in, kick the fan up to high speed to help the A/C out. However, with the compressor cycling in and out quite frequently, I was worried about killing the fan or the relays. The manual gave me the answer: pull the feed for the A/C override from before the low pressure switch on the accumulator. What controls the clutch pulling in and out is the low pressure switch, and the feed to the switch is always hot whenever the mode switch in the cab is in an A/C mode. So, the fan will run high whenever I have the A/C lever in an A/C mode. Much longer on-time for the fan in high, and more happiness by me being cool in the cab. A bonus is that getting to that power feed is easier than getting the clutch feed I was originally planning.
  16. Crawdaddy

    Crawdaddy Moderator

    I just ordered the Mishimoto MMWHS-38-BK temperature sender adapter to go in my upper radiator hose. Hopefully I chose the correct diameter of adapter. Provided everything goes right, I should be putting this all together next weekend.
  17. nonnieselman

    nonnieselman New Member

  18. Crawdaddy

    Crawdaddy Moderator

    I'm sorry this project's gotten stalled, but between life and acquiring parts and working out strategies and methods to make it work, it's gotten put off. I'm hoping to get back on this soon to get it done.

    My initial plans were to run this in a 2-speed setup, but from the looks of it, I got the 1-speed model fan. No big deal, I just can't modulate speed based on need. That will make the wiring easier as it will now just be 1 relay with a couple diodes and 2 feeds: one from the temp switch in the upper radiator hose and the other from the A/C compressor power feed. However, this will most likely make the fan run non-stop when the truck is on since the A/C will virtually always be on in all but the winter. Any thoughts on that?
    Last edited: Sep 26, 2013
  19. Pikey

    Pikey Moderator

    I think that the fan running when the Ac compressor is on is what you want. My 2005 yukon xl came with twin factory installed e fans. When the AC is turned on both run on high. When I shut the ac off either one or both will stop depending on my coolant temp
  20. Crawdaddy

    Crawdaddy Moderator

    I've noticed that in general, it seems that for electric fans, the ground seems to usually be the side that's switched with the relay. Why is that? I was planning on switching the positive, but I could just just as easily switch the ground. Just wondering what the logic was.

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