Defrost System Rebuild


Editor’s Note: Having never done this job on any VW, I was at a loss how to counsel Richard Diaz. My main job was to act as his cheering section. Richard’s solution to this problem is brilliant! Thank you, Richard, for persevering despite your VW War injuries!


Maybe it is a form of Obsessive Compulsive Disorder, but owning a vintage Volkswagen seems to bring out that trait in most of us who own a vintage VW! Living in Southern California there aren’t many days that a heater, windshield wiper, or a defroster are needed, but to not have them work just drives me up the wall and over time I have dedicated a lot of time to making them work as they were designed to work.

When I bought my “Papa’s Slugbug”, about three years ago, two of the long list of things I wanted working before I picked up the car were the heater and the defroster! To close the deal, the seller agreed! Well, he installed the wrong heater boxes, bus heater boxes, and didn’t attach the heater cables from the lever controls at either side of the emergency brake back to the flaps under the rear seat. Then he used a three-way splitter connection, from a 1968 Bug, for the defroster on the passenger side, using the large size hoses for that splitter, which made the passenger side barely work and the driver and center vent not work at all! I fixed the heater by installing the correct heater boxes and connecting the cables! But the defrost system required a little research to figure out, since I did not have a clue that I was missing the two Y-splitters, nor was I aware of how the system was designed to work!


I have been studying the defroster system to figure out how to fix it! What I have learned is that it is a very basic system, but the parts are a little difficult to find. After a Google search on tips to fix the defroster I was emailing my good and knowledgeable friend Jay Salser. Jay and I had a lot of discussion and he offered referrals to locations where I might find the correct “Y” splitters and hoses! Jay is always willing to help any vintage Volkswagen enthusiast and share not only his knowledge, but his resources. Many times he will share parts right out of his parts pile! Jay also is an advocate of keeping the restoration process as original as possible, so he quietly rejected some of the inventive ways others fixed their defrost systems. When Jay’s parts pile came up empty for the Y-splitter, I knew I was in trouble!

After his first referral for the Y-splitters didn’t pan out, Jay referred me to an advertiser on The Samba, Avery’s Aircooled Auto, located in Kelso, Washington. Soon two Y-splitters were ordered and delivered. The Y-splitters have three different hose sizes. The upper defroster hoses; one for the corner defrosters (1-1/4″ inner diameter fits over the corner defroster tube) and one for the center defroster (1″ inner diameter fits into either side of the center defroster tube) were found at Airhead Parts in Ventura, California. The third hose, the largest of the three (1-1/2″ inner diameter fits over the heater channel pipe flange), runs from the bottom of the Y-splitter to the heater channel, was more elusive.

Thanks to Jay’s persistence to find a single source for the three hoses he finally called and talked to Mark at Wolfsburg West. In a pretty excited phone call from Jay on a Friday morning he told me that Mark went out of his way to guide a search of their product site! You see Jay, and I had been trying to navigate the site by typing in what we were looking for in the “search” window and coming up empty.

Other vendors I searched online either did not have them, or only had the defroster hose from the heater channel to the Y-splitter, or the hoses from the Y-splitter to the corners and center. None had all three! None of the main sites I frequent sold the two-way splitter, either new, nor did they have used ones! And, one vendor who specialized in used parts took all my information and never got back to me! Another, who specialized in used parts never got back to me and after my third try to communicate on the phone I realized I had dealt with this vendor before and had a similar, but more serious, experience, so I abandoned further attempts!

Jay and Eric, of, are proponents of documenting system restorations and resources for parts for future restoration work that many of us will be involved in as we keep these fine cars on the road. For that reason I have submitted this article.

My opinion/theory of why Volkswagen Engineers used the varied hose size configuration is to increase the pressure of the warm air pushed by the engine fan to the front of the car to the Y-splitter. Reducing the size of the hose from 1-1/2″ to 1-1/4″ to the corner of the windshield, a relatively short distance, decreases the volume, but increases the flow pressure to blow the warm air into each corner (Venturi Effect) . The distance to the center of the windshield defroster is greater in distance and the reduction to a 1″ diameter hose further increases the flow pressure to travel the increased distance. But, because of this competition for warm air, the center defroster must receive warm air from both heater channels.

Because this same warm air is also pulled from the heater channels to send warm air under the rear passenger area and at the foot area of both the driver and passenger, there is competition for this warm air before it even reaches the windshield defroster! Many times this creates forced choices to be made by the driver to get enough warm air to the windshield to keep a clear view! Sorry, wife and kids, but I have to see where we are going! Fortunately for those of us in Southern California we very rarely have to worry about experiencing those cold temperatures!


Now that parts are in hand it is time to formulate a plan on how to fix my defrost system! Searching The Samba Forums, I found a lot of blogging about this topic. Most people experienced similar problems in finding parts and installing the hose at the heater channel. None had to purchase the Y-splitters.

I had this information prior to my search and how most who tackled this project improvised the parts and installation of the paper hose to the heater channel outlet metal tube. My goal was to use as many VW spec parts as I could find and to figure a way to install that lower hose as it was designed to be installed! But, I was prepared, and willing to improvise!

PARTS/VENDORS: Total Parts $103.10

PN 113-819-723A Defrost/Air Hose, 1-1/4″ inner diameter, goes from Y-Splitter to corner of windshield defrost outlet.

PN 211-255-359 Center Defroster Hose, 1″ inner diameter, goes from Y-splitter to center defrost outlet on dash.

Used Y-splitter (2) (reproduction Splitters are not available).

PN 113-819-723, defroster hose, German. Connects from heater channel to “Y”-splitter. 1-1/2″ inner diameter X 43″ $7.25 ea. (2). I bought two, but I realized that I needed only about 1′ of hose for each side so I recommend purchasing only one hose and cut to length. You still will have extra hose!

PN 113-819-723A, 1-1/4″ inner diameter X 27″ defrost hose, “Y” connector to corner of the windshield.  (2)

PN 211-255-359, 1″ inner diameter X 35″ preheat tube, from “Y” connector to center defrost outlet on the dash.  (2)


Right I away I will admit that this isn’t an easy undertaking! I recommend that you make sure that you want to start this project before you acquire all the parts! I tried, for about two hours, accessing this area with the hood on! Although not impossible, it was very difficult to see in there without a mirror!


And, there is also the bumping-your-head constantly on the hood! So my recommendation is to remove the hood right away and save yourself at least an hour, or two! I also disconnected the hood hinges to give me better visual of the area as well as access.


Be careful, because when reaching into the recess to try to remove old hose and debris you will come across some very sharp metal that will cut you. At one point I had my right hand stuck inside this narrow opening and considered calling the fire department to get my arm out! But, visualizing them cutting my car up with the jaws-of-life scared me enough to force my arm lose with some injury to my forearm and hand!


In my case, I spent a lot of time removing remnants of old hose from each side. Most of the problems I had were on the passenger side because the previous owner used a yellow adhesive (gorilla snot) to attach the over-sized hose he used. You need to be prepared to fashion assisting tools to help dislodge old material.



Although I did hook up my defrost system using VW purchased hose, I still needed to fit the lower hose from the Y-Splitter using a “Not Intended Method”! The lower hose is the largest of the three hoses and just could not be attached to the heater channel outlet flange despite trying to open the hose larger! The area where the flange is located is just too tight to get an adult arm into there to guide and set the hose over the flange! Another issue is that the flange is not directly below, but off to the side, making it very difficult to line-up the hose with the flange.

I had to adapt the hose by placing a 5″ piece of the 1-1/4″ inner diameter hose into the 1-1/2″ inner diameter hose! I left approximately three inches of 1-1/4″ hose extended past the end of the larger hose so that it would slip INTO the flange in lieu of trying to have the 1-1/2″ hose fit OVER the flange. I used some aluminum backed sealing tape I got from a friend in the air conditioning installation business to make the smaller hose fit more tightly inside the larger hose. I then wrapped both hoses to keep them together.


After everything was hooked up and hood replaced I took a test drive! Although it worked, I was a little disappointed that it didn’t work that well! Like I said to Jay, “I am a little deflated, but not defeated!” I will think about this a little more, let my injuries heal, and down the road fine-tune this installation to see if there is blockage, leakage, or anything I can do to increase the airflow! I think the installation looks good, and I did use VW parts!


After some thought, I decided that the bottom hose was extended too far into the metal heater channel outlet flange, preventing a full flow of air into the defrost hoses. Without removing the hood again, I was able to pull the Splitter with its hose slightly upwards.

A test drive proved that I was right. Now air blew strongly through the defrost outlets, even blowing debris and sand (from media blasting the car?) into the cabin.

I happily mark this project DONE!

Posted by Jay Salser

My wife, Neva, and I have been driving and working on VWs since 1976. In fact, we raised our family in these cars. Now, we are retired and enjoy VWs as a hobby. The ’67 Beetle always has been our favorite year. We own a '67 Beetle and a '68 Karmann Ghia.

  1. Great job! I need to work on mine too!

  2. I have a friend who forgot to install the lower hoses to the heater channels when he was restoring his Beetle. He had an experience similar to Richard’s–I remember seeing his arms covered with cuts and scrapes! I really like Richard’s solution–it not only uses VW spec materials, it isn’t something cobbled together. And…it works right. Long live those who work through these knotty problems! jay

  3. Thanks for this…helped me in sourcing the right sizes of tubes and I completed the system without the extensive cuts!

    1. Hello, Tony–Thank you for taking time to post such encouraging words! We are happy to hear that Richard Diaz’ article was helpful. Richard is a great guy! He took the time needed to record step by step his painful experience with the repairs. I am glad that you were able to achieve similar results! Keep enjoying your Volkswagen! jay

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