scotth48

Getting ready to hook up spal fans from Dewitt's. At first I wasn't sure which one was the primary but found that it is the left one (6E3-C12-3 Book 2 FSM). Now these new fans look identical and size compared to the old ones with primary being larger and secondary smaller. Now my question is, do I need to change the fuse as the FSM on the next page show the primary fan with a 30 amp maxifuse and the secondary fan having a 40 amp maxifuse. Should I just leave it the way they are or make them both 30's or both 40's?

WVZR-1

Since you mentioned maxi-fuses you're obviously dealing with a later C4 so I'd suggest you mention the year and since you mentioned "the vendor" - I'd contact them and confirm the installation.

Which fan did you have issues with? Did you do any diagnostics?

I thought DeWitt were a pair of 11" and required relocation of accumulator. You hint that they're different diameters on yours. What part number did you buy?

scotth48

1993 LT1. Relocation of the accumulator is not needed. Using a rubber bushing to space it out from the shroud. When I was at DeWitt's last year I forgot about making spacers for the accumulator. We did make an aluminum bushing/spacer for the top radiator hose to use the original bracket. The new fans are the same size, it is the old one's which are two different sizes. The only issue is what size fuse to use, the 30's for both, or 40's for both or leave it as it is with 30
amp for the primary fan and 40 for the secondary fan. Since the new fans are the same, I would think that 30's would work best for both.

WVZR-1

This is what you mentioned in your first post.

Why would you change anything? You're still utilizing the factory relays OR............?

scotth48

The relays are not the problem. The question is should I switch out the fuses. I did get a reply from John at DeWitt's and he recommends using 30 amp fuses for both.

scotth48

The only issue is what size fuse to use, the 30's for both, or 40's for both or leave it as it is with 30 amp for the primary fan and 40 for the secondary fan. Since the new fans are the same, I would think that 30's would work best for both.[/QUOTE]

Received a message from John at DeWitt's and recommended using 30 amp for both. Relays are the same, just need to remove the 40 amp fuse and install a 30 amp.

WVZR-1

So you buy a 30AMP MAXI but I still don't see the need in changing anything. I'm sure if you were doing a new install that a fuse of 30AMP or greater would be suggested.

The fuses at 30 and 40 are no more an issue than anything else in the circuits.

scotth48

The original primary fan uses a 30 amp so it will blow quicker because of the draw down to protect the wiring. The both new fans have a similar draw, where as the original secondary fan had less draw and could use a 40 amp fuse before it would need to blow to protect the wiring. The wiring is the same for both circuits but the secondary original fan is replaced now with one similar to the primary original that used the30 amp. I would rather have the satisfaction of protecting the wiring from an overload and have the 30 amp blow quicker to protect the wiring from any problem if a the fan were to fail like an internal short.

Hooked on Vettes

Contact Spal tech. support.

Get the fan blade diameter, how many blades, the blade style and cfm. If they can identify the model they can tell you the current ratings and what size fuse to use.

http://www.spalusa.com/

scotth48

I did contact spa, but have not heard back from them. Only from DeWitt's and what John recommended and that is good enough for me.

65Z01

Since the fuse protects the wiring, use the OEM fuses.

If the 30A blows you will need to rewire and use a 40A.

WVZR-1

Since there appears to be NO rush I'd wait for the SPAL reply. Some of their install procedures show different schemes with high, medium and lower profiles with none of the fuse requirements being the same. None are higher than 30 AMP but the medium and low have notes mentioning 20 AMP and 15 AMP respectively.

Their reply might be interesting - post back!

scotth48

The 30 amp fuses will blow before a 40 will!