69 BB Heater hoses W/AC

[Grahame M.]

Hi Everyone,

I hope you are all staying as safe and healthy as you possibly can. We're thing of you here in Oz

I have a late 69 L68 with AC and need to install new heater hoses while the radiator, shroud and fan or removed. The heater core has no hoses attached and i'd like to leave it like that for the moment.

With AC there is a heater control valve that the two hoses are attached too. Please see attached pics.

I've searched the archives but can't find anything specifically on my model vehicle. What i'd like to know is where the hoses route to when the heater core has been removed from the circuit?

I have the AIM but it only gives me the routing with the heater core included. As i'm also trying to fix an over heating problem as previously posted and just want to make sure my current configuration isn't contributing to the problem.

Cheers
Grahame

[Mark E.]

Re: 69 BB Heater hoses W/AC

I also bypassed the heater core to reduce cabin heat in my '70 LS5 AC car- who needs a heater when driving a big block in Texas? To minimize connections (and leaks) I also bypassed the heater control valve. The hose routing is: intake manifold to expansion tank with 5/8" hose; and expansion tank to water pump with 3/4" hose. The connections to the heater core and control valve are plugged to keep dirt out. The heater hose routing to/from the engine looks stock from above.

For '70 at least, both connections on the expansion tank are 3/4", so use either a 3/4" to 5/8" hose adapter or a dual ID heater hose for the connection to the intake manifold. For the 3/4" hose connection at the expansion tank, a tight 90 degree bend is needed. So either add a separate 90 degree elbow or use a 3/4" hose with a 90 degree bend molded on one end.

Photos before AC compressor installation-
IMG_20200413_120052963.jpgIMG_20200413_120130020.jpg

[Grahame M.]

Re: 69 BB Heater hoses W/AC

Thank you for the quick response Mark
Stay safe and healthy.
Grahame

[Grahame M.]

Re: 69 BB Heater hoses W/AC

Sorry, one more question. The routing of the hoses looks like it goes over top of the (yet to be installed) compressor? i have the clamps coming from the US, which should be here this week.

Cheers
Grahame

[Mark E.]

Re: 69 BB Heater hoses W/AC

Yes, both heater hoses route over the compressor. Here's a photo of a 1970 Bloomington Survivor (not mine). 1969 L34 is similar in this regard; I'm not sure about L68.

1970 Bloomington Survivor LS5 80k miles RH.jpg

[Grahame M.]

Re: 69 BB Heater hoses W/AC

Thanks again Mark, much appreciated and have nice night.

Cheers
Grahame