Evaporator Housing Cover Necessary?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

KSSB

Junior Member
Joined
Apr 30, 2025
Posts
8
Reaction score
10
Location
Kansas
First Name
Ty
Truck Year
80, 85
Truck Model
Custom Deluxe, Silverado
Engine Size
250 I6, 6.2 Detroit
This is probably an obvious answer, but I don't know, what I don't know. So here goes.

85 Silverado, 6.2, and the blower doesn't work. I ordered a resistor, switch and blower motor.

As I was looking at it, it appears the evaporator housing has a cover over it that is falling apart, ridiculously easy. Is that cover necessary, as far as needed for function? Or, can I just remove the outer cover and run the bare housing? I don't think I've ever seen one with this cover, so that would tell me it's irrelevant, but again, I don't know what I don't know. It would have to be removed to get to the motor, and I'd need to try to find another if it's required, because there's no way it will be intact if I remove it.

Thanks for the help and sorry if this is a no brainer question.
 

Bextreme04

Full Access Member
Joined
May 13, 2019
Posts
4,550
Reaction score
5,847
Location
Oregon
First Name
Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
This is probably an obvious answer, but I don't know, what I don't know. So here goes.

85 Silverado, 6.2, and the blower doesn't work. I ordered a resistor, switch and blower motor.

As I was looking at it, it appears the evaporator housing has a cover over it that is falling apart, ridiculously easy. Is that cover necessary, as far as needed for function? Or, can I just remove the outer cover and run the bare housing? I don't think I've ever seen one with this cover, so that would tell me it's irrelevant, but again, I don't know what I don't know. It would have to be removed to get to the motor, and I'd need to try to find another if it's required, because there's no way it will be intact if I remove it.

Thanks for the help and sorry if this is a no brainer question.
Picture? I've never seen a cover over the housing that also covered the blower motor.
 

Bextreme04

Full Access Member
Joined
May 13, 2019
Posts
4,550
Reaction score
5,847
Location
Oregon
First Name
Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
This is probably an obvious answer, but I don't know, what I don't know. So here goes.

85 Silverado, 6.2, and the blower doesn't work. I ordered a resistor, switch and blower motor.

As I was looking at it, it appears the evaporator housing has a cover over it that is falling apart, ridiculously easy. Is that cover necessary, as far as needed for function? Or, can I just remove the outer cover and run the bare housing? I don't think I've ever seen one with this cover, so that would tell me it's irrelevant, but again, I don't know what I don't know. It would have to be removed to get to the motor, and I'd need to try to find another if it's required, because there's no way it will be intact if I remove it.

Thanks for the help and sorry if this is a no brainer question.
Also, my blower motor started acting up and it turned out to be a combination of a few things. The power feed for the blower motor goes through the fan switch, the resistor, the relay mounted next to the resistor and the blower motor on the housing, and then into the blower. So anything within that circuit could be causing an issue. Mine would get full voltage to the blower motor, but it screamed and barely moved. It ended up being a bad relay not allowing enough amperage through. There are two relays available and they are interchangeable physically. If you get the wrong one you will immediately blow the fuse for the AC and it won't work.
 

KSSB

Junior Member
Joined
Apr 30, 2025
Posts
8
Reaction score
10
Location
Kansas
First Name
Ty
Truck Year
80, 85
Truck Model
Custom Deluxe, Silverado
Engine Size
250 I6, 6.2 Detroit
Shoot, sorry. I forgot to upload that.
You must be registered for see images attach
 

KSSB

Junior Member
Joined
Apr 30, 2025
Posts
8
Reaction score
10
Location
Kansas
First Name
Ty
Truck Year
80, 85
Truck Model
Custom Deluxe, Silverado
Engine Size
250 I6, 6.2 Detroit
Also, my blower motor started acting up and it turned out to be a combination of a few things. The power feed for the blower motor goes through the fan switch, the resistor, the relay mounted next to the resistor and the blower motor on the housing, and then into the blower. So anything within that circuit could be causing an issue. Mine would get full voltage to the blower motor, but it screamed and barely moved. It ended up being a bad relay not allowing enough amperage through. There are two relays available and they are interchangeable physically. If you get the wrong one you will immediately blow the fuse for the AC and it won't work.
I've never seen a cover either.

I forgot to order the relay next to the resistor. So, I need to order that. This is a very clean truck for an 85, and it's lineage has stayed in the family for 40 years. So, I figured I'd just replace everything in the whole line.
 

KSSB

Junior Member
Joined
Apr 30, 2025
Posts
8
Reaction score
10
Location
Kansas
First Name
Ty
Truck Year
80, 85
Truck Model
Custom Deluxe, Silverado
Engine Size
250 I6, 6.2 Detroit
Also, my blower motor started acting up and it turned out to be a combination of a few things. The power feed for the blower motor goes through the fan switch, the resistor, the relay mounted next to the resistor and the blower motor on the housing, and then into the blower. So anything within that circuit could be causing an issue. Mine would get full voltage to the blower motor, but it screamed and barely moved. It ended up being a bad relay not allowing enough amperage through. There are two relays available and they are interchangeable physically. If you get the wrong one you will immediately blow the fuse for the AC and it won't work.
Also, do you happen to know the difference between the relays, so I know what to look for?
 

Blue Ox

Turning Diesel Fuel Into Fun
Joined
Mar 27, 2018
Posts
5,411
Reaction score
12,676
Location
LI-NY
First Name
Derek
Truck Year
MCMLXXXV
Truck Model
K20HD
Engine Size
6.2L
its part of the extra insulation that diesels got

Exactly. Diesels got a bunch of soundproofing that other engines didn't. I think there was extra jute padding on the inside firewall as well.
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
10,182
Reaction score
7,559
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Exactly. Diesels got a bunch of soundproofing that other engines didn't. I think there was extra jute padding on the inside firewall as well.
yes, hoods would have insulation regardless of being inside or outside opening probably, and regardless of trim

The resonance and drone they were trying hard to tune out, as seen by these and the intake resonator they used

They also benefitted from keeping the heat in the cab (for the ones that did that) because id imagine it can be potentially hard to keep up with the heater if your idling in the extreme cold, so the extra insulation on all trims helped keep you from being cold
I think the cold climate package, which negates the having of AC, does the same thing for the cabin and then replaces your blower fan and controls, possibly the heater core but it may just be the fan
 

Blue Ox

Turning Diesel Fuel Into Fun
Joined
Mar 27, 2018
Posts
5,411
Reaction score
12,676
Location
LI-NY
First Name
Derek
Truck Year
MCMLXXXV
Truck Model
K20HD
Engine Size
6.2L
They also benefitted from keeping the heat in the cab (for the ones that did that) because id imagine it can be potentially hard to keep up with the heater if your idling in the extreme cold, so the extra insulation on all trims helped keep you from being cold

Yep. The price of efficiency.

The mighty TDI has three glow plug elements in the cooling system to provide defrosting in cold weather.

The engine actually rejects so little energy to coolant that it has to be supplemented.

That's some engineering $#it, and why I love Dr. Diesel's invention so much.
 

KSSB

Junior Member
Joined
Apr 30, 2025
Posts
8
Reaction score
10
Location
Kansas
First Name
Ty
Truck Year
80, 85
Truck Model
Custom Deluxe, Silverado
Engine Size
250 I6, 6.2 Detroit
its part of the extra insulation that diesels got
That would explain why I've never seen it before. I've only ran across a couple diesel squares, and honestly didn't pay any attention to that.

I appreciate your help, and the additional information. Thank you to @Blue Ox as well. I'm glad it's not really necessary.

I can already tell, this is going to be a very beneficial forum. Glad I signed up!
 

Bextreme04

Full Access Member
Joined
May 13, 2019
Posts
4,550
Reaction score
5,847
Location
Oregon
First Name
Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
Also, do you happen to know the difference between the relays, so I know what to look for?
I got both from O'reilly. They have a 30/40 Amp one listed or a 15 Amp. I assumed the 30/40Amp was the correct one and it was not. The one I got that was not correct was PN: RY117. I then exchanged it for the(more expensive) PN: RY23, that says it is only rated for 15 Amps and it has been working perfectly ever since. It's been about 3 years now that it has been in there.
 

KSSB

Junior Member
Joined
Apr 30, 2025
Posts
8
Reaction score
10
Location
Kansas
First Name
Ty
Truck Year
80, 85
Truck Model
Custom Deluxe, Silverado
Engine Size
250 I6, 6.2 Detroit
I got both from O'reilly. They have a 30/40 Amp one listed or a 15 Amp. I assumed the 30/40Amp was the correct one and it was not. The one I got that was not correct was PN: RY117. I then exchanged it for the(more expensive) PN: RY23, that says it is only rated for 15 Amps and it has been working perfectly ever since. It's been about 3 years now that it has been in there.
Thank you, SIr.

Edit: Napa has the 15 amp. Thanks again!
 
Last edited:

Latest posts

Forum statistics

Threads
45,619
Posts
987,547
Members
38,704
Latest member
KAR1130
Top