Radio Help

Sean Haas

Well-Known Member
Site Donor $
Messages
155
Reaction score
46
Location
Chicago
Spent the last couple days installing the Retrosound head unit/amp/sub. Everything appeared to be working fine until I took a test drive and the one thing I didn't test was running the A/C while the radio was on - when I switch the A/C blower on the radio turns off. Further detail - power is coming from a dedicated line off the battery (yes in-line fused) through the firewall (via the ignition wire grommet) to a distribution block (one line goes to amp, which in turn feeds head unit, and one line goes to power the subwoofer.) Since nothing is in the way there I don't believe it's the hot wire. Next the switched line is connected into a purple wire/connector, which I believe is the dedicated factory radio connection (this is where the dead Blaupunkt in my car was connected.) It is grounded through the dedicated ground line which I believe was also for the factory radio. In my wiring diagram it looks like this ground eventually runs back to a load shed relay which is also connected to the blower motor (pins 30, 85-87.) Before I open everything back up just wondering if this is causing an issue and I'm losing ground and just changing the ground point would fix it, or if there's something I'm missing.

I do not have the original blower switch as it died, I wired in a 3 speed switch with resistors on the back, in case that's useful.

One other question while I'm at it - what is the quickest way to test if the antennae works - when I yanked the Blaupunkt out the power antennae wire was never connected. I know the trigger wire is low amperage so I didn't want to hook something up that would fry it. The coax was connected to the radio so not sure what was up there.

As an aside, there's barely enough room to get a small amp behind the glovebox, the only reason I was hellbent on doing that and not under the seats or something was because the Retrosound stuff has a plug-n-play harness which is not all that long and I wanted to avoid having to run lines all over. Sound quality is very good although I used Hertz speakers since they fit my old 70's-looking speaker enclosures so I can't vouch for their speakers.
 

Dick Steinkamp

Well-Known Member
Site Donor $
Messages
2,426
Reaction score
2,849
Location
Bellingham, WA
This is a longshot, but....

With the stock electrical system, turning on the AC blower cuts power to the heater blower by energizing the relay #5 in this illustration...

Screen Shot 2022-06-12 at 10.25.00 AM.png


If you have picked up the radio power downstream from this relay it will also cut out the radio when the AC blower is turned on.
 

Sean Haas

Well-Known Member
Site Donor $
Messages
155
Reaction score
46
Location
Chicago
I recall that now. Looking at the diagram I do not see that the purple radio wire runs through that at all. It looks like it just runs back through Fuse 10 which is also wired to the ignition switch. However I see fuse 9, included in your diagram above, does connect back to the same load shed relay that the ground is running to which makes me suspect the ground is an issue.
 

Dick Steinkamp

Well-Known Member
Site Donor $
Messages
2,426
Reaction score
2,849
Location
Bellingham, WA
One test you might try is to unplug the wire from connector #6 to relay #5 and see if turning on the AC blower still turns off the radio.
 

Sean Haas

Well-Known Member
Site Donor $
Messages
155
Reaction score
46
Location
Chicago
So I worked backward checking all connections and eventually had to take the whole effing thing apart, having buttoned everything up the day before. Turns out the head unit, which is supposed to ground back through the "plug-n-play" wire harness to the amp, was actually not. If the metal body of the head unit was touching the metal bracket that the transmission stuff and trim pieces attach to it created a ground and worked. If it came off that it did not. Why the A/C blower switch was turning it off I'm not sure except it's cramped in there and I suppose part of the switch was contacting part of the radio and lifting the ground in some manner. Anywho, I made a ground wire with some ring connectors and grounded the radio body to the bracket and bob's yer uncle, stereo system all works and blower works. Also I found the old thread on testing antennae so that will be a project for another day. Man that was not fun when it's in the 90's with 90% humidity.
 
Top