Yes - use a diode =>1A, =>25V is fine - lots of choices, better if there is a way to make all three switches get you close to 100% fan? is that an option? That's essentially what stock does.

Alan

 

Contrary to popular belief, water conducts almost no electricity, so if the controller is turning on, it’s not from water, I don’t know of any controller that will do that. It’s actually the resulting corrosion that harms most controllers, not the water itself. The dccontrols are actually popular with the rock crawler crowed because they’re submersible, they’re very well known to operate and survive under water.

With regard to putting the controller in a box, it will cause the dccontrol unit to cycle on and off and will most likely destroy the flexalite unit if Ben follows his recommendation, as I don’t believe they have over temperature protection.

There is a good reason for this, stagnant air is one of the best thermal insulators available, it’s what makes house insulation work and what will keep either controller from dissipating virtually any heat generated. I’m pretty sure most people understand that, as I’ve only had one other customer in the past eleven years do this. I’ve only seen one pwm controller that the manufacturer decided to put in a box, and I never saw it last for more than a few minutes under any reasonable load. Temperature rise = power dissipation * thermal resistance. The thermal resistance of stagnant air is for all practical purposes infinite.

There are at least two things wrong with this installation, the controller mounted in the box, and the relay. As said, the relay probably won’t take out the new controller, but what you now have, given the original control box is still connected, is a 500V+ spike hitting both the original control box and the installed controller if the relay ever triggers. This is the reason I was looking for an alternative.

http://www.repeater-builder.com/tech...uppression.pdf

I always like to try and help, but I can only give advice and, given the posts here, the OP clearly hasn’t listened to a word of what I’ve tried to convey to him either by email or here on the forum. With that, along with the level of decisions made here, this looks to be an inevitable train wreck that I’m not going to be able to stop, so good luck with this guys, I think you’re really going to need it.

 

Interesting is my word of choice I will apply here.
Yes, I clearly haven't been listening.
When you and Alan were discussing the spike issue and Alan referred to utilizing the Suppressor on the CE Panel, I posed a question on this. I have been reading ALL things very closely - some things were over my head and I even made (tried to) a comical quip about it.

I have been reading very closely every word posted on this issue that I had started a thread on.

I feel much relieved to now know that I am not in danger of the 500V spike for the original units are sitting on my workbench and are not part of the currently running system which is working well. But you knew this for if one condescends to another for not listening to what one has said, then you must listen to all that another says so as to take that position.

I always try to be helpful and courteous in the Forum. When I speak incorrectly on a matter I go out of my way to acknowledge, correct, and own it as fast as I can. I am not the insolent type to do otherwise.

 

Thanks again Alan.
Would be good to go to 100% when one of these gets tripped - means there is an issue needing to be addressed. Actually the 50% fans through the dc unit are very brisk - seems almost like the 'full' fans I had with the original units, but maybe I am mis-perceiving.

Next up is the box removal on the good advisement, then a shower.

 

This is the closest I can find to that.

I wanted to get the car back on the road so after I finished the job, tested it at idle, I took it for some test runs. Will remove the controller when I can

What I'm saying is that about 90% of what we discussed is the benefit of designing for good thermal management That's the reason for the heat sink. So now you have a heat sink with 24 square inches of surface area in a box with what looks like 8 1/8" holes in it. Probably a little condescending in my response, sorry for that, a little bit frustrating seeing how this is going

 

No, I test ran the unit days ago and have been driving the car with the unit in place as seen in the first picture of it since then. The box was put in last night, and will be removed this morning.

The old controllers are out of the car so not worried re the spike any longer.
No more questions here from me.
Not at all frustrated.
Thanks.

 

councilmen: We've decided to give all the citizens a thousand dollars
Eddie Albert: You can't do that, we'll be bankrupt, I won't be held responsible
councilmen: You are responsible, you're the mayer
Eddie Albert: Well, then we aren't going to do it
councilmen: You don't get to vote

 

Craig

Recapping: the spike comes when the new clutch relay coil or clutch coil are switched off - it has nothing to do with the old controller.

A. You need to make sure that the 'AC on' feed to the new module comes from the direct clutch coil driver and the feed to the LH should also be from here with the CE suppressor (diode) remaining connected there - as in the stock case.

B. The stock AC head unit (integrated) relay coil driver circuit has a protection diode as does its original clutch output - which now become a protection diode across your added relay coil.

So: B. is OK - make sure A. is configured as noted here.

Alan

 

Thanks Alan.
I really wasn't understanding what you and Brian were delving into.
I had posted and asked earlier if H15 as seen on the 87 WD was where I tie into the Suppressor for it's output to the dc unit - that didn't come out right - how do I do/arrange these connections involving the Suppressor ?

 

Alan, would I be protected if I tied the feed to the new dc unit off H15 at the CE or even the line to the evaporator (freeze switch) or low pressure switch which is off H15 from the Suppressor, and not directly off the compressor clutch feed ? Is my assumption from my interpretation of the WD correct ?

 

You added 2 new relays here if I understand correctly:

1) A new relay to beef up the AC compressor clutch drive, I assume this is either in/on the AC head unit or somewhere else (CE panel/ under hood) - what did you actually do here?
2) A new relay to combine the 3 switch inputs we discussed.

Here we are talking just about 1)

On an '87 The AC active (post freeze switch) connects to H15. Which internal to CE also connects to the suppressor diode (to ground). Via W24 it also connects to the LH and via M12 to the compressor clutch coil.

Your new relay needs to be placed before the connection to CE on H15 or before the freeze switch

OR if its now located on the CE panel:

Disconnect the rear connection to pin H15 - this loose wire becomes your new relay's 87 connection. Connect your new relay's coil 86 connection to the rear pin of H15. Connect the AC input to the DC fan controller to the clutch coil connection

Make sense? goal is to avoid changing the relative positions of the protection circuits to the loads

Alan

 

Alan,
My secondary AC relay is located in a black box fixed right next to the air pump filter. Its power is off the jump post. Its ground is MP I. Its switch is the compressor Black and its 87 is to the compressor.

Because it is already there (under the hood), I'm going to tie into the Suppressor from its freeze switch connection into the AC circuitry. So its basically switching the relay by its input (86), and it is its output via 87 to complete the circuit. The dc controller AC feed then gets attached to the little Black compressor line.
Would this be the correct arrangement ?

 

Alan,
Would actually be easier to tie into the M12 Suppressor line going to the low pressure switch. Can I tap into this for my 86 'in', 87 'out' to/from the relay and tie in the dc unit AC input from the compressor Black line as described.
Sorry for what appears to be such elementary questions - I just want to be sure I'm doing/thinking clearly and correctly on it.
Thanks,
Craig

Add: I know they are both Black lines at the low pressure switch, but I will verify by continuity which one is to the compressor clutch - the other will be the feed to/from the Suppressor.

 

Finished the wiring to my pre-existing secondary relay for AC compressor clutch activation with Suppressor protection. Normally, where one did not have such a relay, one would tie in the dc controller AC activation line to the Black compressor activation line - Suppressor protection is part of the normal AC circuit - all will be protected from potential compressor clutch coil generated voltage spikes.
For those who have such a secondary relay utilized, here is what I did.

I utilized the line to/from the CE panel Suppressor at its connection to the low pressure AC switch - this was easier for me to work with in light of where I had the relay installed - one can also use the Suppressor feed at the freeze switch - it is the single Violet/Green wire there. At the low pressure switch there are two Black lines connected - one to 14 pin connector to feed the compressor clutch - the other goes to the Suppressor. I verified which was which by continuity testing of the compressor feed line - once established, I worked with the other.
The Suppressor line feed to the switch was cut - the proximal end tied into pin 86 of the relay. The distal end of the Suppressor line was then tied into pin 87 of the relay. The circuit with Suppressor protection was now maintained. My pre-existing 86 feed to relay (switch off the compressor feed) was then attached to the 87 feed off the relay which went directly to the compressor - the feed to the AC input activation on the dc controller was attached here.

I was fortunate I did not have issue with spiking up to this point.
I thank both electrical Masters for pointing this out.
Now, the job is done and now...

 

Brian,
I do hope you view this.
I felt badly by our discord here. You felt as if I was disregarding your advisements, and not acting on them. I completely did not understand what you and Alan were talking about regarding the intricacies of the electronics. I really do/did appreciate your help from our first conversation to our last. I hope there is peace between us.
Craig