88-94 5.7 Suburban A/C Diagnosis and Tuning

[Sawlty]

@Wildblue19

I've got the e fan parts in the mail.

Side note, if anyone happens to have an anemometer or knows what the approximate vent air speed should be drop a reply.

In my 93, on high, recirc off, the average across all front vents was right around 10mph with the vehicle static. Measured with the fan parallel to the vent face and flush against it Recirc on, it was about 11mph. Rear fan blew harder on high with the middle row vents averaging about 15mph.

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Which parts did you order for your efan project. I have a 94 K2500 that is having same issues you are having. Eerily similar!!

Thinking about this helper fan as well!

Thanks and good luck!!

Also—weather permitting…I’m going to evacuate and recharge per @L31MaxExpress recommemdations posted earlier in this thread.

I still have the rear air box open after replacing the TXV. Will have that buttoned up on Saturday.

I’ve replaced EVERYTHING with the exception of both evaporators and all lines.

There is awesome stuff in this thread. Thanks for pointing me here @1998_K1500_Sub Much appreciated.

@L31MaxExpress I believe you might be near my neck of the woods. Do you do automotive AC work??

Thanks everyone and have a fantastic day!

 

[Wildblue19]

@Wildblue19

Which parts did you order for your efan project

621-300 part number fan

 

[1998_K1500_Sub]

Side note, if anyone happens to have an anemometer or knows what the approximate vent air speed should be drop a reply.

I have used an anemometer on my 1998 Suburban and Dad's 1995 K1500 RCLB, so as to compare the exit velocity at the front air vents.

I have notes, somewhere, if I can only remember where

 

[1998_K1500_Sub]

621-300 part number fan

@Sawlty, I’ve attached a picture you posted earlier of your Suburban for reference.

The fan (above) will fit on your Suburban on the driver’s side, if you’ve removed that extra non-OE transmission cooler that a previous owner added. Your OE transmission cooler on the passenger’s side prevents the fan from being installed there.

That fan is typically installed on the passenger’s side, tho I’m not aware that it matters. The only constraint seems to be that the fan can not interfere with either the OE optional transmission cooler (IIRC resident on the passenger’s side) or OE optional engine oil cooler (IIRC resident on the driver’s side).

 

[Sawlty]

@1998_K1500_Sub

I will be removing the secondary oil transmission cooler from my unit.

As for the oil cooler…is that what you see in the photo that you posted of my unit on the drivers side radiator stansion? Will the fan interfere with it or will it interfere with the fan?

I’m only guessing that this is an oil cooler. I haven’t owned my 94 long enough to determine exactly what it is. The AC system has monopolized my research and project time for the past month or so!

Glad to see that it will work for me. It’s in order.

While flipping thru the LMC catalog tonight while at work, I see that they offer a condenser fan switch! Again, assuming, that I will need something of this sort so that the fan will run when the AC clutch is engaged.

Will this electric fan really move more cfm of air across the condenser than the stock fan/fan clutch?

 

[1998_K1500_Sub]

I will be removing the secondary oil transmission cooler from my unit.

See the attached picture. I assume you mean to remove the one on the right.

The one on the left is the OE transmission cooler.

While flipping thru the LMC catalog tonight while at work, I see that they offer a condenser fan switch! Again, assuming, that I will need something of this sort so that the fan will run when the AC clutch is engaged.

Agreed.

There are a number of ways to control the fan, based upon e.g., the high-side pressure, condenser temperature, and / or vehicle speed.

On later model GMT400s (1996+? certainly 1998) one can use the ECU for fan control, perhaps the earlier models support this as well; I believe they may.

@Frank Enstein has posted on this topic, maybe he will comment. @PlayingWithTBI may have some comments too, he’s an Arizona resident and knowledgeable about AC on older GMT400s.

Finally, SEE THIS THREAD and the threads and members it references.

Thread 'Aux AC Fan for 99 5.7 Tahoe - Wiring?'
https://www.gmt400.com/threads/aux-ac-fan-for-99-5-7-tahoe-wiring.57156/

Will this electric fan really move more cfm of air across the condenser than the stock fan/fan clutch?

IMHO the aux electric fan is more of a benefit at low vehicle speed / low engine (fan) RPM, particularly periods when the fan clutch may not be fully engaged.

 

[PlayingWithTBI]

As for the oil cooler…is that what you see in the photo that you posted of my unit on the drivers side radiator stansion?

If you're talking about the tall, skinny one, that's your power steering cooler.

. @PlayingWithTBI may have some comments too, he’s an Arizona resident and knowledgeable about AC on older GMT400s.

I can't tell from the picture, is that a parallel flow condenser? My biggest bang for the buck was a parallel flow condenser and the 11 blade fan with a severe duty clutch @L31MaxExpress suggested, along with a good flush and only 8 oz PAG oil (in a single system).

As discussed in other threads, proper amount of coolant is critical in these systems. One word of caution, you can lower the amount of refrigerant to the point you get excellent cooling at the expense of reduced oil flow and, possibly hurting your compressor. These things don't have a crankcase like the old piston types of yesteryear.

 

[1998_K1500_Sub]

If you're talking about the tall, skinny one, that's your power steering cooler.

Did you ever devise a means of controlling the aux electric van?

Can it be done with the ECU on any 1995 and earlier GMT400s?

 

[PlayingWithTBI]

Did you ever devise a means of controlling the aux electric van?

Can it be done with the ECU on any 1995 and earlier GMT400s?

I have not messed with an aux fan - yet. I've seen setups which are adjustable so you can play with that and wire in a relay to turn them on when the compressor comes on. In my EBL it has a setting to turn off the fan(s) when reaching a certain MPH but, it doesn't have a temp setting. IDK about the 7427 PCM though.

 

[Sawlty]

If you're talking about the tall, skinny one, that's your power steering cooler.


I can't tell from the picture, is that a parallel flow condenser? My biggest bang for the buck was a parallel flow condenser and the 11 blade fan with a severe duty clutch @L31MaxExpress suggested, along with a good flush and only 8 oz PAG oil (in a single system).

As discussed in other threads, proper amount of coolant is critical in these systems. One word of caution, you can lower the amount of refrigerant to the point you get excellent cooling at the expense of reduced oil flow and, possibly hurting your compressor. These things don't have a crankcase like the old piston types of yesteryear.

Any specific info on the 11-blade fan and severe duty clutch? Like part numbers?

@PlayingWithTBI Yes. It’s an after market parallel condenser.

@1998_K1500_Sub

The cooler on the right is the after market cooler. Yes. Thanks for clarifying.

So, flush and go back with only 8oz of PAG 150. Install the 11-blade fan and severe duty fan clutch. Ensure that my recirc and blend doors properly seal and are in working condition.

Anything else that you guys recommend?